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My goal is to dynamically put some arbitrary text into an HICON image (at runtime.) I'm using the following code:
//Error checks are omitted for brevity
//First create font
LOGFONT lf = {0};
lf.lfHeight = -58;
lf.lfWeight = FW_NORMAL;
lf.lfOutPrecision = OUT_TT_PRECIS; //Use TrueType fonts for anti-alliasing
lf.lfQuality = CLEARTYPE_QUALITY;
lstrcpy(lf.lfFaceName, L"Segoe UI");
HFONT hFont = ::CreateFontIndirect(&lf);
//HICON hIcon = original icon to use as a source
//I'm using a large 256x256 pixel icon
hIcon = (HICON)::LoadImage(theApp.m_hInstance, MAKEINTRESOURCE(IDI_ICON_GREEN_DIAMOND), IMAGE_ICON, 256, 256, LR_DEFAULTCOLOR);
ICONINFO ii = {0};
::GetIconInfo(hIcon, &ii);
BITMAP bm = {0};
::GetObject(ii.hbmColor, sizeof(bm), &bm);
SIZE szBmp = {bm.bmWidth, bm.bmHeight};
HDC hDc = ::GetDC(hWnd);
HDC hMemDC = ::CreateCompatibleDC(hDc);
HGDIOBJ hOldBmp = ::SelectObject(hMemDC, ii.hbmColor);
HGDIOBJ hOldFont = ::SelectObject(hMemDC, hFont);
::SetBkMode(hMemDC, TRANSPARENT);
::SetTextColor(hMemDC, RGB(255, 0, 0)); //Red text
//Draw text
//NOTE that DrawText API behaves in a similar way
::TextOut(hMemDC, 0, 0, L"Hello", 5);
::SelectObject(hMemDC, hOldFont);
::SelectObject(hMemDC, hOldBmp);
//We need a simple mask bitmap for the icon
HBITMAP hBmpMsk = ::CreateBitmap(szBmp.cx, szBmp.cy, 1, 1, NULL);
ICONINFO ii2 = {0};
ii2.fIcon = TRUE;
ii2.hbmColor = ii.hbmColor;
ii2.hbmMask = hBmpMsk;
//Create updated icon
HICON hIcon2 = ::CreateIconIndirect(&ii2);
//Cleanup
::DeleteObject(hBmpMsk);
::DeleteDC(hMemDC);
::ReleaseDC(hWnd, hDc);
::DeleteObject(ii.hbmColor);
::DeleteObject(ii.hbmMask);
::DeleteObject(hFont);
and then I can display the icon in my window from OnPaint() handler (so that I can see how it turns out) as such:
::DrawIconEx(dc.GetSafeHdc(), 0, 0,
hIcon2,
256, 256, NULL,
::GetSysColorBrush(COLOR_BTNFACE),
DI_NORMAL);
So here's what I get:
To see what's going on pixel-wise in my hIcon2 I called GetDIBits on its ii.hbmColor from the code above. The resulting pixel array where my word "Hello" was supposed to be shown looked like this:
The pixels are encoded as BGRA in that memory dump, so the 4th byte in each DWORD stands for transparency: 0=transparent, FF=opaque. But in this case TextOut doesn't fill out transparency, or leaves it as 0, which is interpreted as "fully transparent." Instead it seems to pre-multiply it into the RGB colors themselves.
Note that if I keep looking further down the same bitmap, where the green diamond begins, the image pixels seem to have transparency bytes set correctly:
Any idea how to draw text so that the API could set those transparency bytes?
EDIT: As was suggested below I tried the following GDI+ method:
HGDIOBJ hOldBmp = ::SelectObject(hMemDC, ii.hbmColor);
Graphics grpx(hMemDC);
RectF rcfTxt(0.0f, 0.0f, (REAL)szBmp.cx, (REAL)szBmp.cy);
Font gdiFont(L"Segoe UI", 58.0f, FontStyleRegular, UnitPixel);
SolidBrush gdiBrush(Color(255, 0, 0));
StringFormat gdiSF;
gdiSF.SetAlignment(StringAlignmentNear);
gdiSF.SetFormatFlags(StringFormatFlagsNoWrap);
gdiSF.SetHotkeyPrefix(HotkeyPrefixNone);
//The reason I was using GDI was because I was setting
//spacing between letters using SetTextCharacterExtra()
//Unfortunately with GDI+ this does not work!
HDC hTmpDC = grpx.GetHDC();
::SetTextCharacterExtra(hTmpDC, -4); //This doesn't do anything!
grpx.ReleaseHDC(hTmpDC);
grpx.DrawString(L"Hello", 5, &gdiFont, rcfTxt, &gdiSF, &gdiBrush);
::SelectObject(hMemDC, hOldBmp);
and besides not being able to set character spacing (which I could with GDI using SetTextCharacterExtra) here's what I got (slightly enlarged for visibility):
So clearly still an issue with transparency.
Taken from an old post by Microsoft MVP Mike D Sutton here.
When you create a DC it initially has default 'stock' objects selected
into it, including the stock 1*1*1 Bitmap. Since there is a Bitmap
already selected into the DC when you call DrawText() it will still
try and render to it even though pretty much everything (apart from
one pixel) will be clipped.
What you need to do is to create a Bitmap,
either DDB or DIBSection, and select that into your DC before drawing
to it.
First though you need to find the size of your Bitmap since you
want it large enough to display your text in, so for that you use the
DrawText() call again on the initial DC but include the DT_CALCRECT
flag. What this does is rather than drawing anything it simply
measures how large the text is and dumps that into the RECT you pass
the call. From here you can go ahead and create your DIBSection using
those dimensions and select it into your DC. Finally perform your
existing DrawText ()call (you may also want to use SetBkMode/Color())
which will render the text to the DIBSection from which you can get at
the data.
This seems to work pretty well here:
HBITMAP CreateAlphaTextBitmap(LPCSTR inText, HFONT inFont, COLORREF inColour) {
int TextLength = (int)strlen(inText);
if (TextLength <= 0) return NULL;
// Create DC and select font into it
HDC hTextDC = CreateCompatibleDC(NULL);
HFONT hOldFont = (HFONT)SelectObject(hTextDC, inFont);
HBITMAP hMyDIB = NULL;
// Get text area
RECT TextArea = {0, 0, 0, 0};
DrawText(hTextDC, inText, TextLength, &TextArea, DT_CALCRECT);
if ((TextArea.right > TextArea.left) && (TextArea.bottom > TextArea.top)) {
BITMAPINFOHEADER BMIH;
memset(&BMIH, 0x0, sizeof(BITMAPINFOHEADER));
void *pvBits = NULL;
// Specify DIB setup
BMIH.biSize = sizeof(BMIH);
BMIH.biWidth = TextArea.right - TextArea.left;
BMIH.biHeight = TextArea.bottom - TextArea.top;
BMIH.biPlanes = 1;
BMIH.biBitCount = 32;
BMIH.biCompression = BI_RGB;
// Create and select DIB into DC
hMyDIB = CreateDIBSection(hTextDC, (LPBITMAPINFO)&BMIH, 0, (LPVOID*)&pvBits, NULL, 0);
HBITMAP hOldBMP = (HBITMAP)SelectObject(hTextDC, hMyDIB);
if (hOldBMP != NULL) {
// Set up DC properties
SetTextColor(hTextDC, 0x00FFFFFF);
SetBkColor(hTextDC, 0x00000000);
SetBkMode(hTextDC, OPAQUE);
// Draw text to buffer
DrawText(hTextDC, inText, TextLength, &TextArea, DT_NOCLIP);
BYTE* DataPtr = (BYTE*)pvBits;
BYTE FillR = GetRValue(inColour);
BYTE FillG = GetGValue(inColour);
BYTE FillB = GetBValue(inColour);
BYTE ThisA;
for (int LoopY = 0; LoopY < BMIH.biHeight; LoopY++) {
for (int LoopX = 0; LoopX < BMIH.biWidth; LoopX++) {
ThisA = *DataPtr; // Move alpha and pre-multiply with RGB
*DataPtr++ = (FillB * ThisA) >> 8;
*DataPtr++ = (FillG * ThisA) >> 8;
*DataPtr++ = (FillR * ThisA) >> 8;
*DataPtr++ = ThisA; // Set Alpha
}
}
// De-select bitmap
SelectObject(hTextDC, hOldBMP);
}
}
// De-select font and destroy temp DC
SelectObject(hTextDC, hOldFont);
DeleteDC(hTextDC);
// Return DIBSection
return hMyDIB;
}
If you need an example of how to call it then try something like this
(inDC is the DC to render to):
void TestAlphaText(HDC inDC, int inX, int inY) {
const char *DemoText = "Hello World!\0";
RECT TextArea = {0, 0, 0, 0};
HFONT TempFont = CreateFont(50, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "Arial\0");
HBITMAP MyBMP = CreateAlphaTextBitmap(DemoText, TempFont, 0xFF);
DeleteObject(TempFont);
if (MyBMP) { // Create temporary DC and select new Bitmap into it
HDC hTempDC = CreateCompatibleDC(inDC);
HBITMAP hOldBMP = (HBITMAP)SelectObject(hTempDC, MyBMP);
if (hOldBMP) {
BITMAP BMInf; // Get Bitmap image size
GetObject(MyBMP, sizeof(BITMAP), &BMInf);
// Fill blend function and blend new text to window
BLENDFUNCTION bf;
bf.BlendOp = AC_SRC_OVER;
bf.BlendFlags = 0;
bf.SourceConstantAlpha = 0x80;
bf.AlphaFormat = AC_SRC_ALPHA;
AlphaBlend(inDC, inX, inY, BMInf.bmWidth, BMInf.bmHeight,
hTempDC, 0, 0, BMInf.bmWidth, BMInf.bmHeight, bf);
// Clean up
SelectObject(hTempDC, hOldBMP);
DeleteObject(MyBMP);
DeleteDC(hTempDC);
}
}
}
All credit to answer and code go to original posters on that forum, I've simply reposted it so that this answer will be valid if the links die.
This reply is coming almost 3 years after the question was posted, but people still consult these things long into the future. So I'll explain what's happening.
DrawText (and other GDI text functions) will work on a transparent bitmap. The text is not coming out black even though it displays that way. The alpha channel is set to 0 on all pixels the text draws to, overriding whatever alpha you had set previously. If you set an alpha value in SetTextColor the text will render all black. If you're feeling ambitious you can run through pixel by pixel and target anything not your fill color (which requires a single fill color) but the problem then becomes one of the nature of ClearType being overridden and all alphas are set to whatever you set them to. The text ends up looking very funky. If you use a constant alpha for your background fill you can simply do a blanket run across the entire bitmap's bits after the text is drawn and reset all the alpha values. Since you have to read a byte to determine if it's background or not, you might as well just set every pixel's alpha to whatever the standard alpha is for that image and bypass the slow compares. This works reasonably well and I've found it to be very acceptable. In this day and age, MS should have taken care of this long ago but it's not to be.
https://learn.microsoft.com/en-us/windows/win32/gdiplus/-gdiplus-antialiasing-with-text-use
Gdiplus::Bitmap bmp( your_Width, your_Height, PixelFormat64bppARGB);
//PixelFormat64bppARGB ARGB needed
FontFamily fontFamily(L"Arial");
Font font(&fontFamily, 29, FontStyleRegular, UnitPoint);
Gdiplus::RectF rectF(00.0f, 10.0f, your_Width, your_Height);
StringFormat stringFormat;
SolidBrush solidBrush(Color(63, 0, 0, 255));
stringFormat.SetAlignment(StringAlignmentCenter);
//solidBrush Color(63, 0, 0, 255) ARGB neede
graphics.SetTextRenderingHint(TextRenderingHintAntiAlias);
graphics.DrawString("your_text", -1, &font, rectF, &stringFormat, &solidBrush);
//TextRenderingHintAntiAlias this needed
I'm trying to load individual cards from a spritesheet of cards based on suit and rank but I'm unsure of how to construct a new Bitmap object from cutting out Rectangle coordinates in the source image. I'm using <windows.h> currently and trying to find a simple way to accomplish this. I'm looking for something like this:
HBITMAP* twoOfHearts = CutOutFromImage(sourceImage, new Rectangle(0, 0, 76, 116));
From source: http://i.stack.imgur.com/WZ9Od.gif
Here's a function I played with the other week for more-or-less this same task. In my case, I wanted to return a HBRUSH that could be used with FillRect. In that instance, we still need to create a bitmap of the area of interest, before then going on to create a brush from it.
In your case, just return the dstBmp instead. spriteSheet is a global that has had a 256x256 spritesheet loaded. I've hardcoded the size of my sprites to 16x16, you'd need to change that to something like 81x117.
Here's some code that grabs a copy of the required area and some more that uses these 'stamps' to draw a level map. That said - there are all kinds of problems with this approach. Speed is one, excessive work is another one that impacts on the first. Finally, scrolling a window drawn like this produces artefacts.
// grabs a 16x16px section from the spriteSheet HBITMAP
HBRUSH getSpriteBrush(int col, int row)
{
HDC memDC, dstDC, curDC;
HBITMAP oldMemBmp, oldDstBmp, dstBmp;
curDC = GetDC(HWND_DESKTOP);
memDC = CreateCompatibleDC(NULL);
dstDC = CreateCompatibleDC(NULL);
dstBmp = CreateCompatibleBitmap(curDC, 16, 16);
int xOfs, yOfs;
xOfs = 16 * col;
yOfs = 16 * row;
oldMemBmp = (HBITMAP)SelectObject(memDC, spriteSheet);
oldDstBmp = (HBITMAP)SelectObject(dstDC, dstBmp);
BitBlt(dstDC,0,0,16,16, memDC, xOfs,yOfs, SRCCOPY);
SelectObject(memDC, oldMemBmp);
SelectObject(dstDC, oldDstBmp);
ReleaseDC(HWND_DESKTOP, curDC);
DeleteDC(memDC);
DeleteDC(dstDC);
HBRUSH result;
result = CreatePatternBrush(dstBmp);
DeleteObject(dstBmp);
return result;
}
void drawCompoundSprite(int x, int y, HDC paintDC, char *tileIndexes, int numCols, int numRows)
{
int mapCol, mapRow;
HBRUSH curSprite;
RECT curDstRect;
for (mapRow=0; mapRow<numRows; mapRow++)
{
for (mapCol=0; mapCol<numCols; mapCol++)
{
int curSpriteIndex = tileIndexes[mapRow*numCols + mapCol];
int spriteX, spriteY;
spriteX = curSpriteIndex % 16;
spriteY = curSpriteIndex / 16;
curDstRect.left = x + 16*mapCol;
curDstRect.top = y + 16 * mapRow;
curDstRect.right = curDstRect.left + 16;
curDstRect.bottom = curDstRect.top + 16;
curSprite = getSpriteBrush(spriteX, spriteY);
FillRect(paintDC, &curDstRect, curSprite);
DeleteObject(curSprite);
}
}
}
The latter function has since been replaced with the following:
void drawCompoundSpriteFast(int x, int y, HDC paintDC, unsigned char *tileIndexes, int numCols, int numRows, pMapInternalData mData)
{
int mapCol, mapRow;
HBRUSH curSprite;
RECT curDstRect;
HDC memDC;
HBITMAP oldBmp;
memDC = CreateCompatibleDC(NULL);
oldBmp = (HBITMAP)SelectObject(memDC, mData->spriteSheet);
for (mapRow=0; mapRow<numRows; mapRow++)
{
for (mapCol=0; mapCol<numCols; mapCol++)
{
int curSpriteIndex = tileIndexes[mapRow*numCols + mapCol];
int spriteX, spriteY;
spriteX = curSpriteIndex % mData->tileWidth;
spriteY = curSpriteIndex / mData->tileHeight
// Draw sprite as-is
// BitBlt(paintDC, x+16*mapCol, y+16*mapRow,
// mData->tileWidth, mData->tileHeight,
// memDC,
// spriteX * 16, spriteY*16,
// SRCCOPY);
// Draw sprite with magenta rgb(255,0,255) areas treated as transparent (empty)
TransparentBlt(
paintDC,
x+mData->tileWidth*mapCol, y+mData->tileHeight*mapRow,
mData->tileWidth, mData->tileHeight,
memDC,
spriteX * mData->tileWidth, spriteY*mData->tileHeight,
mData->tileWidth, mData->tileHeight,
RGB(255,0,255)
);
}
}
SelectObject(memDC, oldBmp);
DeleteObject(memDC);
}
I have printing code that draws grid on the paper.
Grid has 4 columns, and they have equal horizontal length. Height of the cell is tenth of the paper size. Total number of rows is unknown but I know for a fact that there will be at least one row.
Each cell has same physical size-> width is quarter of the paper width, and height is one tenth of the paper height. Maximum number of characters that can fit into cell is 50.
The problem I face is choosing proper font size so text of maximum length can fit into cell.
Browsing through MSDN documentation and WinAPI examples, I saw that they use GetTextExtPoint32 for similar purposes, but this works only if font already exists and is selected into device context, which is not the case here.
The only thing that crossed my mind was to create "dummy font", see if the example text can fit into cell, and then adjust it's size if the test fails. I have also found this blog that recommends interesting approach to this problem, but being inexperienced I can't decide if "this is the proper way to go".
Can you recommend a correct solution for my problem?
EDITED on June, 30th 2014:
Below is the sample function that draws grid and paints upper left cell in light gray since that cell will contain sample text. That way we can visually validate the success of our drawing code:
// hWnd is the window that owns the property sheet.
HRESULT GDI_PRINT(HWND hWnd)
{
HRESULT hResult;
PRINTDLGEX pdx = {0};
LPPRINTPAGERANGE pPageRanges = NULL;
// Allocate an array of PRINTPAGERANGE structures.
pPageRanges = (LPPRINTPAGERANGE) GlobalAlloc(GPTR, 10 * sizeof(PRINTPAGERANGE));
if (!pPageRanges)
return E_OUTOFMEMORY;
// Initialize the PRINTDLGEX structure.
pdx.lStructSize = sizeof(PRINTDLGEX);
pdx.hwndOwner = hWnd;
pdx.hDevMode = NULL;
pdx.hDevNames = NULL;
pdx.hDC = NULL;
pdx.Flags = PD_RETURNDC;
pdx.Flags2 = 0;
pdx.ExclusionFlags = 0;
pdx.nPageRanges = 0;
pdx.nMaxPageRanges = 10;
pdx.lpPageRanges = pPageRanges;
pdx.nMinPage = 1;
pdx.nMaxPage = 1000;
pdx.nCopies = 1;
pdx.hInstance = 0;
pdx.lpPrintTemplateName = NULL;
pdx.lpCallback = NULL;
pdx.nPropertyPages = 0;
pdx.lphPropertyPages = NULL;
pdx.nStartPage = START_PAGE_GENERAL;
pdx.dwResultAction = 0;
// Invoke the Print property sheet.
hResult = PrintDlgEx(&pdx);
if ( ( hResult == S_OK ) && ( pdx.dwResultAction == PD_RESULT_PRINT ) )
{
// User clicked the Print button,
// so use the DC and other information returned in the
// PRINTDLGEX structure to print the document.
//======= Various initializations ==========//
DOCINFO diDocInfo = {0};
diDocInfo.cbSize = sizeof( DOCINFO );
diDocInfo.lpszDocName = L"Testing printing...";
int pageWidth = GetDeviceCaps( pdx.hDC, HORZRES ),
pageHeight = GetDeviceCaps( pdx.hDC, VERTRES );
//===================== IMPORTANT !!! ==========================//
// Must test this on real printer !!! //
// For now testing is done in XPS and MS OneNote2007 //
//==============================================================//
//================== end of initialization =====================//
if( StartDoc( pdx.hDC, &diDocInfo ) > 0 )
{
if( StartPage( pdx.hDC ) > 0 )
{
//===== creating red pen that will draw grid =====//
LOGBRUSH lb;
lb.lbColor = RGB( 255, 0, 0 );
lb.lbHatch = 0;
lb.lbStyle = BS_SOLID;
HPEN hPen = ExtCreatePen( PS_COSMETIC | PS_SOLID, 1, &lb, 0, NULL);
HGDIOBJ oldPen = SelectObject( pdx.hDC, hPen );
// create test font
HFONT font, oldFont;
long lfHeight = -MulDiv( 14,
GetDeviceCaps( pdx.hDC, LOGPIXELSY ),
72 );
font = CreateFont( lfHeight, 0, 0, 0,
FW_BOLD, TRUE, FALSE, FALSE,
0, 0, 0,
0, 0, L"Microsoft Sans Serif" );
oldFont = SelectFont( pdx.hDC, font );
SetBkMode( pdx.hDC, TRANSPARENT );
SetTextColor( pdx.hDC, RGB( 255, 0, 0 ) );
// testing rectangle -> top left cell of the grid
RECT rcText;
rcText.left = 0;
rcText.top = 0;
rcText.right = pageWidth / 4;
rcText.bottom = pageHeight / 10;
// fill destination rectangle with gray brush
// so we can visually validate rectangle coordinates
FillRect( pdx.hDC, &rcText, (HBRUSH)GetStockObject(LTGRAY_BRUSH) );
// implement solution mentioned in the comment to this question
SIZE s;
::GetTextExtentPoint32( pdx.hDC,
L"Хидрогеотермална енергија Хидрогеотермална енерги",
wcslen( L"Хидрогеотермална енергија Хидрогеотермална енерги" ),
&s );
// select old font back and dispose test font
SelectObject( pdx.hDC, oldFont );
DeleteObject( font );
// adjust font height
lfHeight *= s.cy / ( rcText.bottom - rcText.top );
// now we can create proper font
font = CreateFont( lfHeight, 0, 0, 0,
FW_BOLD, TRUE, FALSE, FALSE,
0, 0, 0,
0, 0, L"Microsoft Sans Serif" );
oldFont = SelectFont( pdx.hDC, font );
// draw text in test rectangle
DrawTextEx( pdx.hDC,
L"Хидрогеотермална енергија Хидрогеотермална енерги",
wcslen( L"Хидрогеотермална енергија Хидрогеотермална енерги" ),
&rcText, DT_CENTER | DT_WORDBREAK | DT_NOCLIP, NULL );
//============== draw a testing grid ===============//
// draw vertical lines of the grid
for( int i = 0; i <= pageWidth; i += pageWidth / 4 )
{
MoveToEx( pdx.hDC, i, 0, NULL );
LineTo( pdx.hDC, i, pageHeight );
}
// draw horizontal lines of the grid
for( int j = 0; j <= pageHeight; j += pageHeight / 10 )
{
MoveToEx( pdx.hDC, 0, j, NULL );
LineTo( pdx.hDC, pageWidth, j );
}
// no need for pen anymore so delete it
SelectObject( pdx.hDC, oldPen );
DeleteObject( hPen );
// no need for font, delete it
SelectFont( pdx.hDC, oldFont );
DeleteFont( font );
if( EndPage( pdx.hDC ) < 0 )
// for now pop a message box saying something went wrong
MessageBox( hWnd, L"EndDoc failed!", L"Error", MB_OK );
}
EndDoc( pdx.hDC );
}
}
if (pdx.hDevMode != NULL)
GlobalFree(pdx.hDevMode);
if (pdx.hDevNames != NULL)
GlobalFree(pdx.hDevNames);
if (pdx.lpPageRanges != NULL)
GlobalFree(pPageRanges);
if (pdx.hDC != NULL)
DeleteDC(pdx.hDC);
return hResult;
}
To use this function, just launch it on button press/menu selection or whatever.
The results in XPS seem consistent, but I get strange results in MS OneNote 2007 which following images illustrate:
Font size is 14 :
Font size is 20 :
Font size is 20, but scaling from the above function was applied :
END OF EDIT
EDITED on July, 6th 2014:
The third picture from above edit was the result of GDI using default height value because the result of my mathematical adjustment for font height was 0. Once zero is passed to CreateFont mentioned behavior is expected.
After performing proper casting from double to int I got nearly perfect output -> last letter in the string barely exceeds the limit. I will continue to try improving this formula since I believe is promising. If anybody has another mathematical solution feel free to post it.
END OF EDIT
If further info / edit is required, leave a comment and I will react as soon as possible.
There are multiple issues involved.
The biggest problem I see is in this line:
lfHeight *= s.cy / ( rcText.bottom - rcText.top );
These are all integers. In C and C++, division with integers results in truncation toward zero. So if the result of the division "should" be 3.7, you'll end up with 3, which can be a pretty crude approximation.
Another problem is that GetTextExtentPoint32 does not wrap text, but DrawText does. So you're measuring the text as though you're going to print it as a single line, and you actually draw it as multiple lines. Instead of using GetTextExtendPoint32, you can measure the height with DrawText by DT_CALCRECT flag.
Putting these together, you want to measure your text like this:
WCHAR szText[] = L"Хидрогеотермална енергија Хидрогеотермална енерги";
RECT rcText;
rcText.left = 0;
rcText.top = 0;
rcText.right = pageWidth / 4;
rcText.bottom = top;
const DWORD options = DT_CENTER | DT_WORDBREAK | DT_NOCLIP;
DrawTextEx( pdx.hDC, szText, -1, &rcText, options | DT_CALCRECT, NULL);
// Because we used DT_CALCRECT, the DrawTextEx call didn't draw anything,
// but it did adjust the bottom of rcText to account for the actual height.
double actual_height = static_cast<double>(rcText.bottom - rcText.top);
double desired_height = pageHeight / 10.0;
double ratio = desired_heigth / actual_height;
// Scale the font height by the ratio, and round it off to the nearest int.
lf.lfHeight = static_cast<int>(lf.lfHeight * ratio + 0.5);
Okay. Basically, I start off with the suggested pointSize (14 in your code) and try to draw the text using the supplied bounding rect. If the text is too large, I go into an iterative loop that decreases the pointsize and measures again until the text will fit into the bounding rect.
If, on the other hand, the text is 'too small' I go into a loop that gradually increases it's size until it is too large. Once I reach this point, I decrease the point-size by 2 and return.
The reduction by 2 is a kludge or hack. I noticed that at times the size was reported as being equal to or smaller than the reported size of the bounding rect, yet still some characters would protrude past the edge of the bounding rect.
A better solution would make use of the DrawTextEx function to both calculate the size and draw the text. This would be better since you could make use of the iLeftmargin and iRightMargin members of the DRAWTEXTPARAMS struct that is passed to that function. Whether you wished to have a margin on each side, or simply wanted to add a single character's width, that you then halved when drawing the text would depend entirely on the desired outcome. I also added the DT_EXTERNALLEADING flag to obtain a small margin above/below the text, though there isn't one for vertical padding, so you'd have to make use of the margin attributes I mention.
Since the DT_VCENTER flag doesn't work with multi-line text, you'd also need to vertically offset the text yourself if you wished it to be vertically centered. You'd just have to offset the rect used for actually drawing the text by half of the difference between the area bounding rect's height and the text bounding rect's height.
I could have used a function like this for a few projects, so thanks for the impetus to actually exercise the grey matter and work it out!
Lastly, I used an interactive demo - one that responded to the WM_PAINT message of a (empty) dialog box. Since a HDC can be treated more-or-less the same whether it be for a printer or the screen, it provided a much quicker way of investigating the result.
Output when plugged into your code: (via cutePDF virtual printer)
Code:
int rectWidth(RECT &r)
{
return (r.right - r.left) + 1;
}
int rectHeight(RECT &r)
{
return (r.bottom - r.top) + 1;
}
void measureFunc(int pointSize, HDC hdc, RECT &pRectBounding, WCHAR *textToDraw, WCHAR *fontFaceName, int &resultWidth, int &resultHeight)
{
int pixelsPerInchY = GetDeviceCaps(hdc, LOGPIXELSY);
int logHeight = -MulDiv(pointSize, pixelsPerInchY, 72);
RECT tmpRect = pRectBounding;
HFONT old, tmp = CreateFont( logHeight, 0, 0, 0, FW_BOLD, TRUE, FALSE, FALSE, 0, 0, 0, 0, 0, fontFaceName );
old = (HFONT)SelectObject(hdc, tmp);
DrawText(hdc, textToDraw, -1, &tmpRect, DT_CENTER | DT_WORDBREAK | DT_NOCLIP | DT_CALCRECT| DT_EXTERNALLEADING );
SelectObject(hdc, old);
DeleteObject(tmp);
resultWidth = rectWidth(tmpRect);
resultHeight = rectHeight(tmpRect);
}
HFONT getMaxFont(HDC hdc, WCHAR *fontName, WCHAR *textToDraw, RECT boundingRect)
{
int maxWidth = rectWidth(boundingRect), maxHeight = rectHeight(boundingRect);
int curWidth, curHeight, pointSize=14;
measureFunc(pointSize, hdc, boundingRect, textToDraw, fontName, curWidth, curHeight);
if ( (curWidth>maxWidth) || (curHeight>maxHeight) )
{
bool tooLarge = true;
while (tooLarge)
{
pointSize--;
measureFunc(pointSize, hdc, boundingRect, textToDraw, fontName, curWidth, curHeight);
if ((curWidth>maxWidth)||(curHeight>maxHeight))
tooLarge = true;
else
tooLarge = false;
}
}
else
{
bool tooSmall = true;
while (tooSmall)
{
pointSize++;
measureFunc(pointSize, hdc, boundingRect, textToDraw, fontName, curWidth, curHeight);
if ( (curWidth<maxWidth) && (curHeight<maxHeight) )
tooSmall = true;
else
tooSmall = false;
}
if ((curWidth>maxWidth) || (curHeight>maxHeight))
{
pointSize-=2;
}
}
int pixelsPerInchY = GetDeviceCaps( hdc, LOGPIXELSY );
int curFontSize;
HFONT result;
curFontSize = -MulDiv(pointSize, pixelsPerInchY, 72);
result = CreateFont(curFontSize, 0, 0, 0, FW_BOLD, TRUE, FALSE, FALSE, 0, 0, 0, 0, 0, fontName );
return result;
}
BOOL CALLBACK DlgMain(HWND hwndDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
switch(uMsg)
{
case WM_INITDIALOG:
{
}
return TRUE;
case WM_SIZE:
InvalidateRect(hwndDlg, NULL, true);
return 0;
case WM_ERASEBKGND:
{
RECT mRect;
GetClientRect(hwndDlg, &mRect);
HBRUSH redBrush = CreateSolidBrush(RGB(255,0,0));
FillRect((HDC)wParam, &mRect, redBrush);
DeleteObject(redBrush);
}
return true;
case WM_PAINT:
{
HDC hdc;
PAINTSTRUCT ps;
HFONT requiredFont, oldFont;
WCHAR *textToDraw = L"Хидрогеотермална енергија Хидрогеотермална енерги";
WCHAR *fontFace = L"Microsoft Sans Serif";
RECT boundingRect, dlgRect;
hdc = BeginPaint(hwndDlg, &ps);
oldFont = (HFONT)GetCurrentObject(hdc, OBJ_FONT);
GetClientRect(hwndDlg, &dlgRect);
SetRect(&boundingRect, 0,0, rectWidth(dlgRect) / 4, rectHeight(dlgRect) / 10);
FillRect(hdc, &boundingRect, (HBRUSH)GetStockObject(WHITE_BRUSH));
requiredFont = getMaxFont(hdc, fontFace, textToDraw, boundingRect);
SelectObject(hdc, requiredFont);
SetBkMode(hdc, TRANSPARENT);
DrawText(hdc, textToDraw, -1, &boundingRect, DT_CENTER | DT_WORDBREAK | DT_NOCLIP | DT_EXTERNALLEADING );
SelectObject(hdc, oldFont);
DeleteObject(requiredFont);
EndPaint(hwndDlg, &ps);
}
return false;
case WM_CLOSE:
{
EndDialog(hwndDlg, 0);
}
return TRUE;
case WM_COMMAND:
{
switch(LOWORD(wParam))
{
}
}
return TRUE;
}
return FALSE;
}
I import a picture(.bmp or .jpeg) as the background of a client view in MFC.
When I click Open, function CDrawToolView::OnFileOpen() open a window to choose a picture, then I use ShowBitmap(CDC* pDC,CString strPicPath) and ShowPic(CDC* pDC,CString strPicPath) to load the picture as backgroud and adjust the size of client view to fit the picture.
I want to set the picture translucent, so the background looks softer. Could some one help me or give some suggestion, thanks.
Here is my code:
void CDrawToolView::ShowBitmap(CDC* pDC,CString strPicPath)
{
HBITMAP hBitmap=(HBITMAP)LoadImage(NULL,strPicPath,IMAGE_BITMAP,0,0,LR_CREATEDIBSECTION|LR_DEFAULTSIZE|LR_LOADFROMFILE);
m_bitmap.Detach();
m_bitmap.Attach(hBitmap);
CRect rect;
GetClientRect(&rect);
CDC dcImage;
if (!dcImage.CreateCompatibleDC(pDC))
{
return;
}
BITMAP bm;
m_bitmap.GetBitmap(&bm);
dcImage.SelectObject(&m_bitmap);
pDC->StretchBlt(0,0,rect.right,rect.bottom,&dcImage,0,0,bm.bmWidth,bm.bmHeight,SRCCOPY);
}
void CDrawToolView::ShowPic(CDC* pDC,CString strPicPath)
{
if(!m_MyImage.IsNull())
m_MyImage.Destroy();
HRESULT hResult=m_MyImage.Load(strPicPath);
int iWidth=m_MyImage.GetWidth();
int iHeight=m_MyImage.GetHeight();
m_MyImage.Draw(pDC->m_hDC,0,0,iWidth,iHeight);
CRect client(0, 0, iWidth, iHeight);
client.bottom=client.bottom+::GetSystemMetrics(SM_CYMENU)+::GetSystemMetrics(SM_CYEDGE)*2;
client.right=client.right+::GetSystemMetrics(SM_CXEDGE)*2;
CFrameWnd* pFrame = GetParentFrame();
pFrame->CalcWindowRect(&client);
int width = client.Width();
int height = client.Height();
int y = (::GetSystemMetrics(SM_CYSCREEN) - height) / 2 + 100;
int x = (::GetSystemMetrics(SM_CXSCREEN) - width) / 2;
pFrame->SetWindowPos( NULL, x, y, width, height, SWP_NOACTIVATE | SWP_NOZORDER );
}
Use AlphaBlend instead of StretchBlt
CDC::AlphaBlend
Set SourceConstantAlpha in your BLENDFUNCTION struct to something like 128 (halfway between transparent and opaque), then adjust until it looks good.
AlphaFormat should be zero unless your usa a 32-bit bitmap with an alpha channel.
I have an application that has drawn a grid using CDC (it has text, rectangle, and bitmaps). I want to take a screenshot of that finished grid when it is saved and use that screenshot as a "preview" for the file.
How can I take a screenshot of my application and save it?
Thank you,
Answer is here
void CScreenShotDlg::OnPaint()
{
// device context for painting
CPaintDC dc(this);
// Get the window handle of calculator application.
HWND hWnd = ::FindWindow( 0, _T( "Calculator" ));
// Take screenshot.
PrintWindow( hWnd,
dc.GetSafeHdc(),
0 );
}
Ultimately I ended up doing it this way because I wanted to capture even the hidden parts of the window (since the content extends beyond the screen and requires scrolling):
CDC* WindowToCaptureDC = AfxGetMainWnd()->GetWindowDC();
CDC CaptureDC;
CDC MemDC;
MemDC.CreateCompatibleDC(WindowToCaptureDC);
CaptureDC.CreateCompatibleDC(WindowToCaptureDC);
CBitmap CaptureBmp;
CBitmap ResizeBmp;
int pWidth = grid.tableWidth + grid.marginLeft*2;
int pHeight = grid.tableHeight + grid.marginBottom;
CaptureBmp.CreateCompatibleBitmap( WindowToCaptureDC, pWidth, pHeight);
CaptureDC.SelectObject(&CaptureBmp);
CBrush brush(RGB(255, 255, 255));
CaptureDC.SelectObject(&brush);
CaptureDC.Rectangle(0, 0, pWidth, pHeight);
///Drew items into CaptureDC like I did for OnDraw HERE///
double width = //desired width;
double height = //desired width;
//maintain aspect ratio
if(pWidth!=width || pHeight!=height)
{
double w = width/pWidth;
double h = height/pHeight;
if(w < h)
height = height*w;
else
width = width*h;
}
ResizeBmp.CreateCompatibleBitmap(WindowToCaptureDC, width, height);
MemDC.SelectObject(&ResizeBmp);
MemDC.StretchBlt(0, 0, width, height, &CaptureDC, 0, 0, pWidth, pHeight, SRCCOPY);
CImage TempImageObj;
TempImageObj.Attach((HBITMAP)ResizeBmp.Detach());
CString filePath = _T("LOCATION\\image.bmp");
TempImageObj.Save(filePath);