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Trying to convert 32,24,16,8 bit images to their grayscale presentation. I read about using BitBlt, but maybe exist some light way built-in opportunity
in GDI+?
Code:
#include <vector>
...
class gdiplus_init
{
ULONG_PTR token;
public:
gdiplus_init()
{
Gdiplus::GdiplusStartupInput tmp;
Gdiplus::GdiplusStartup(&token, &tmp, NULL);
}
~gdiplus_init()
{
Gdiplus::GdiplusShutdown(token);
}
};
bool getbits(const wchar_t *filename, Gdiplus::PixelFormat pixelformat,
std::vector<BYTE> &bitmapinfo, std::vector<BYTE> &bits, int &w, int &h)
{
gdiplus_init init;
WORD bpp = 0;
int usage = DIB_RGB_COLORS;
int palettesize = 0;
switch(pixelformat)
{
case PixelFormat8bppIndexed:
bpp = 8;
usage = DIB_PAL_COLORS;
palettesize = 256 * sizeof(RGBQUAD);
break;
case PixelFormat16bppRGB555: bpp = 16; break;
case PixelFormat16bppRGB565: bpp = 16; break;
case PixelFormat24bppRGB: bpp = 24; break;
case PixelFormat32bppRGB: bpp = 32; break;
default:return false;
}
auto src = Gdiplus::Bitmap::FromFile(filename);
if(src->GetLastStatus() != Gdiplus::Status::Ok)
return false;
auto dst = src->Clone(0, 0, src->GetWidth(), src->GetHeight(),
pixelformat);
w = src->GetWidth();
h = src->GetHeight();
HBITMAP hbitmap;
Gdiplus::Color color;
dst->GetHBITMAP(color, &hbitmap);
//allocate enough memory for bitmapinfo and initialize to zero
//it's sizeof BITMAPINFO structure + size of palette
bitmapinfo.resize(sizeof(BITMAPINFO) + palettesize, 0);
//fill the first 6 parameters
BITMAPINFO* ptr = (BITMAPINFO*)bitmapinfo.data();
ptr->bmiHeader.biSize = sizeof(BITMAPINFOHEADER); //don't skip
ptr->bmiHeader.biWidth = w;
ptr->bmiHeader.biHeight = h;
ptr->bmiHeader.biPlanes = 1;
ptr->bmiHeader.biBitCount = bpp;
ptr->bmiHeader.biCompression = BI_RGB;
//magic formula to calculate the size:
//this is roughly w * h * bytes_per_pixel, it's written this way
//to account for "bitmap padding"
DWORD size = ((w * bpp + 31) / 32) * 4 * h;
//allocate memory for image
bits.resize(size, 0);
//finally call GetDIBits to fill bits and bitmapinfo
HDC hdc = GetDC(0);
GetDIBits(hdc, hbitmap, 0, h, &bits[0], (BITMAPINFO*)&bitmapinfo[0], usage);
ReleaseDC(0, hdc);
//cleanup
delete src;
delete dst;
return true;
}
void CMFCApplicationColorsView::OnDraw(CDC* pDC)
{
...
std::vector<BYTE> bi; //automatic storage
std::vector<BYTE> bits;
int w, h;
//24-bit test
if(getbits(L"c:\\test\\24bit.bmp", PixelFormat24bppRGB, bi, bits, w, h))
StretchDIBits(dc, 0, 0, w, h, 0, 0, w, h,
bits.data(), (BITMAPINFO*)bi.data(), DIB_RGB_COLORS, SRCCOPY);
//8-bit test
if(getbits(L"c:\\test\\8bit.bmp", PixelFormat8bppIndexed, bi, bits, w, h))
StretchDIBits(dc, 0, 220, w, h, 0, 0, w, h,
bits.data(), (BITMAPINFO*)bi.data(), DIB_PAL_COLORS, SRCCOPY);
}
You can draw the GDI+ directly with various transformation. Use Gdiplus::Graphics to draw on device context.
For grayscale conversion, RGB values all have to be the same. Gdiplus::ColorMatrix can transform the colors. Green is usually more important, it gets more weight.
void draw(CDC *pdc)
{
//this line should be in OnCreate or somewhere other than paint routine
Gdiplus::Bitmap source(L"file.jpg");
//gray scale conversion:
Gdiplus::ColorMatrix matrix =
{
.3f, .3f, .3f, 0, 0,
.6f, .6f, .6f, 0, 0,
.1f, .1f, .1f, 0, 0,
0, 0, 0, 1, 0,
0, 0, 0, 0, 1
};
Gdiplus::ImageAttributes attr;
attr.SetColorMatrix(&matrix,
Gdiplus::ColorMatrixFlagsDefault, Gdiplus::ColorAdjustTypeBitmap);
Gdiplus::Graphics gr(pdc->GetSafeHdc());
Gdiplus::REAL w = (Gdiplus::REAL)source.GetWidth();
Gdiplus::REAL h = (Gdiplus::REAL)source.GetHeight();
Gdiplus::RectF rect(0, 0, w, h);
gr.DrawImage(&source, rect, 0, 0, w, h, Gdiplus::UnitPixel, &attr);
}
Note, I used rough values for grayscale matrix. See the answer mentioned in comment for a better matrix.
To convert the file, the process is similar, except use Gdiplus::Graphics to create memory dc and save it.
int GetEncoderClsid(const WCHAR* format, CLSID* clsid)
{
int result = -1;
UINT num = 0; // number of image encoders
UINT size = 0; // size of the image encoder array in bytes
Gdiplus::GetImageEncodersSize(&num, &size);
if(size)
{
Gdiplus::ImageCodecInfo* codec = (Gdiplus::ImageCodecInfo*)(malloc(size));
GetImageEncoders(num, size, codec);
for(UINT j = 0; j < num; ++j)
if(wcscmp(codec[j].MimeType, format) == 0)
{
*clsid = codec[j].Clsid;
result = j;
}
free(codec);
}
return result;
}
bool convert_grayscale(const wchar_t *file_in, const wchar_t *file_out)
{
CStringW extension = PathFindExtensionW(file_out);
extension.Remove(L'.');
extension.MakeLower();
if(extension == L"jpg") extension = L"jpeg";
extension = L"image/" + extension;
CLSID clsid;
if(GetEncoderClsid(extension, &clsid) == -1)
return false;
Gdiplus::Bitmap source(file_in);
if(source.GetLastStatus() != Gdiplus::Status::Ok)
return false;
Gdiplus::REAL w = (Gdiplus::REAL)source.GetWidth();
Gdiplus::REAL h = (Gdiplus::REAL)source.GetHeight();
Gdiplus::RectF rect(0, 0, w, h);
Gdiplus::Bitmap copy((INT)w, (INT)h, source.GetPixelFormat());
Gdiplus::ColorMatrix matrix =
{
.3f, .3f, .3f, 0, 0,
.6f, .6f, .6f, 0, 0,
.1f, .1f, .1f, 0, 0,
0, 0, 0, 1, 0,
0, 0, 0, 0, 1
};
Gdiplus::ImageAttributes attr;
attr.SetColorMatrix(&matrix,
Gdiplus::ColorMatrixFlagsDefault, Gdiplus::ColorAdjustTypeBitmap);
Gdiplus::Graphics gr(©);
gr.DrawImage(&source, rect, 0, 0, w, h, Gdiplus::UnitPixel, &attr);
auto st = copy.Save(file_out, &clsid);
return st == Gdiplus::Status::Ok;
}
...
convert_grayscale(L"source.jpg", L"destination.jpg");
I want to take a capture of part of screen and save it into BMP. To save picture I plan with SOIL. Bit bliting functions I get here.
Code:
bool saveScreen(string path)
{
string name;
SYSTEMTIME sm;
GetSystemTime(&sm);
name = to_string(sm.wHour) + to_string(sm.wMinute) + to_string(sm.wSecond) + to_string(sm.wMilliseconds)
+ "_" + to_string(sm.wDay) + to_string(sm.wMonth) + to_string(sm.wYear);
path = /*path + "/" +*/ name + ".bmp";
const char *charPath = path.c_str();
BITMAPINFO bmi;
auto& hdr = bmi.bmiHeader;
hdr.biSize = sizeof(bmi.bmiHeader);
hdr.biWidth = screenWidth;
hdr.biHeight = screenHeight;
hdr.biPlanes = 1;
hdr.biBitCount = 32;
hdr.biCompression = BI_RGB;
hdr.biSizeImage = 0;
hdr.biXPelsPerMeter = 0;
hdr.biYPelsPerMeter = 0;
hdr.biClrUsed = 0;
hdr.biClrImportant = 0;
unsigned char* bitmapBits;
HDC hdc = GetDC(NULL);
HDC hBmpDc = CreateCompatibleDC(hdc);
BITMAP bm;
HBITMAP hBmp = CreateDIBSection(hdc, &bmi, DIB_RGB_COLORS, (void**)&bitmapBits, nullptr, 0);
SelectObject(hBmpDc, hBmp);
BitBlt(hBmpDc, 0, 0, screenWidth, 1024, hdc, 0, 0, SRCCOPY);
vector< unsigned char > buf(screenWidth* screenHeight* 3);
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glReadPixels(0, 0, screenWidth, screenHeight, GL_RGB, GL_UNSIGNED_BYTE, bitmapBits);
int texture = SOIL_save_image(charPath, SOIL_SAVE_TYPE_BMP, screenWidth, screenHeight, 3, bitmapBits);
return texture;
}
On output I get this:
Broken BMP
It looks as RGBA/RGB issue, but I don't set RGBA nowhere.
What I missed in the code? It's the right way to get screenshot?
You create 32 bpp image, however pass 3 to SOIL_save_image indicating that it is 24 bpp image.
Here's my code, using SDL 2.0.4 on OSX 10.11.4:
SDL_Surface *output_surface = SDL_CreateRGBSurface(0, width, height, 8, 0, 0, 0, 0);
SDL_Texture *output_texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STREAMING, width, height);
SDL_Color c[256];
// Setting each color to red as a test.
for(u8 i = 255; i--;) {
c[i].r = 255;
c[i].g = 0;
c[i].b = 0;
}
SDL_SetPaletteColors(output_surface->format->palette, c, 0, 256);
Then later...
SDL_Rect r = {
.x = 0,
.y = 0,
.w = width,
.h = height
};
// Doesn't fill with red.
SDL_FillRect(output_surface, &r, 4);
SDL_UpdateTexture(output_texture, NULL, output_surface->pixels, output_surface->pitch);
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, output_texture, NULL, NULL);
SDL_RenderPresent(renderer);
What I would expect to see is the full window all red but I'm getting something entirely different. Changing the color number passed to SDL_FillRect shows that I'm getting a grayscale palette (0 is black, 255 is white) even though SDL_SetPaletteColors doesn't return an error and i've looped through output_surface->format->palette->colors to verify the palette's been changed.
What am I missing here?
edit: I was asked to post an entire program. Here it is:
int main(int argc, const char *argv[]) {
SDL_Window *window = NULL;
SDL_Renderer *renderer = NULL;
SDL_Surface *output_surface = NULL;
SDL_Texture *output_texture = NULL;
int width = 640;
int height = 480;
if(SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER) < 0) return 0;
window = SDL_CreateWindow("Sample", SDL_WINDOWPOS_CENTERED, SDL_WINDOWPOS_CENTERED, width, height, 0);
renderer = SDL_CreateRenderer(window, -1, SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_ACCELERATED);
output_surface = SDL_CreateRGBSurface(0, width, height, 8, 0, 0, 0, 0);
output_texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STREAMING, width, height);
SDL_Color c[256];
for(u8 i = 255; i--;) {
c[i].r = 255;
c[i].g = 0;
c[i].b = 0;
c[i].a = 255;
}
SDL_SetPaletteColors(output_surface->format->palette, c, 0, 255);
SDL_Rect r = {
.x = 0,
.y = 0,
.w = width,
.h = height
};
bool running = true;
while(running) {
SDL_Event event;
while(SDL_PollEvent(&event)) {
switch(event.type){
case SDL_KEYDOWN:
running = false;
break;
}
}
SDL_FillRect(output_surface, &r, 124);
SDL_UpdateTexture(output_texture, NULL, output_surface->pixels, output_surface->pitch);
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, output_texture, NULL, NULL);
SDL_RenderPresent(renderer);
}
SDL_FreeSurface(output_surface);
SDL_DestroyTexture(output_texture);
SDL_DestroyRenderer(renderer);
SDL_DestroyWindow(window);
SDL_Quit();
return 0;
}
Passing 0 to SDL_FillRect is black, 255 is white, and any number in-between is a shade of grey.
Alright, found the solution.
Remove this line:
output_texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_RGB24, SDL_TEXTUREACCESS_STREAMING, width, height);
And instead add this line somewhere after the call to SDL_SetPaletteColors or after you change the surfaces' pixels (like in the game loop):
output_texture = SDL_CreateTextureFromSurface(renderer, output_surface);
In C# and XNA, you can create a 1x1 texture like this:
Texture2D white_pixel;
white_pixel = new Texture2D(GraphicsDevice, 1, 1);
white_pixel.SetData<Color[]>(new Color{ Color.White });
// Sorry if I got the syntax wrong, it's been a while
Then later on, you can arbitrarily draw the pixel to any size and color by doing this:
spriteBatch.Begin();
spriteBatch.Draw(white_pixel, new Rectangle(0, 0, width, height), Color.Whatever);
spriteBatch.End();
What is the equivalent in SDL?
SDL_Texture *tex = nullptr;
SDL_CreateTexture(renderer,
Uint32 format, // What do I put here
int access, // and here
1
1);
// Not sure if this is correct
SDL_SetTextureColorMod(tex,
255,
255,
255)
SDL_Rect rect;
rect.x = 0;
rect.y = 0;
rect.w = 10;
rect.h = 10;
SDL_RenderCopy(renderer, tex, nullptr, &rect);
SDL_PIXELFORMAT_RGB24/SDL_PIXELFORMAT_BGR24 for format and SDL_TEXTUREACCESS_STATIC for access would be a good start.
Or you could just draw a colored rectangle directly via SDL_SetRenderDrawColor() and SDL_RenderFillRect().
I'm trying to make a very little and simple snippet with SDL. This one works like a charm :
SDL_Window * window = SDL_CreateWindow("SDLTest", 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT, SDL_SWSURFACE);
screen = SDL_GetWindowSurface(window);
SDL_Color color={0,0,0};
TTF_GlyphMetrics(font, ch, &minx, &maxx, &miny, &maxy, NULL);
SDL_Surface * car =TTF_RenderGlyph_Blended(font,ch,color);
SDL_Rect textRect = {offsetX, offsetY, 0, 0};
if(SDL_BlitSurface( car, NULL, glyph, &screen ))
qDebug() << SDL_GetError();
and this one doesn't work at all :
SDL_Surface * glyph = NULL;
SDL_Surface * car = TTF_RenderGlyph_Blended(font,ch,color);
qDebug() << TTF_GetError();
SDL_Rect textRect = {0, 0, car->w, car->h};
if(SDL_BlitSurface( car, NULL, glyph, &textRect ))
qDebug() << SDL_GetError();
TTF_GetError() return nothing so I assume TTF_RenderGlyph_Blended works well and SDL_GetError() send me this :
SDL_UpperBlit: passed a NULL surface
::::::::::::::::: EDIT ::::::::::::::::::
Ok, I've fix the NULL problem, but the blit is not good yet:
ch = 66;
SDL_Surface * glyph = TTF_RenderUTF8_Blended(font, "Z", color);
SDL_UnlockSurface(glyph);
SDL_Surface * car = TTF_RenderGlyph_Blended(font,ch,color);
SDL_Rect textRect = {0, 0, car->w, car->h};
qDebug() << SDL_BlitSurface(car, NULL, glyph, &textRect);
qDebug() << SDL_BlitSurface(glyph, NULL, screen, &textRect);
Should display B but go Z instead...
SDL_BlitSurface requires source surface (your car variable) and destination surface (your glyph variable). Your first snippet doesn't show how and where is glyph created, but your second snippet explicitly sets glyph to NULL.
You should assign created surface to glyph before using it in SDL_BlitSurface function.
Edit:
For rendering glyphs on surface, first create new surface, fill it with background color, and then blit glyph on it. You can use rectangle to define blit position if you want:
SDL_Surface * glyph = SDL_CreateRGBSurface(0, 100, 100, 32, 0, 0, 0, 0);
SDL_FillRect(glyph, NULL, SDL_MapRGB(glyph->format, 255, 255, 255);
ch = 66;
SDL_Surface * car = TTF_RenderGlyph_Blended(font, ch, color);
qDebug() << SDL_BlitSurface(car, NULL, glyph, NULL);
qDebug() << SDL_BlitSurface(glyph, NULL, screen, NULL);
Manual says you shouldn't call for locked surfaces when using SDL_BlitSurface(). Try to SDL_UnlockSurface() before call SDL_BlitSurface() for your surfaces. And for more information check what is the returned value of SDL_BlitSurface(). Before that you have to check for source surface to see whether it's filled or not, and try to use SDL_FillRect() on destination surface before blitting and see what happens.
Although, check for correct surface format:
http://wiki.libsdl.org/SDL_BlitSurface#Remarks
As MahamGM said, there was a format issue which is solved now :
Uint32 rmask, gmask, bmask, amask;
rmask = 0x000000ff;
gmask = 0x0000ff00;
bmask = 0x00ff0000;
amask = 0xff000000;
ch = 65;
SDL_Surface * glyph = SDL_CreateRGBSurface(0,screen->w,screen->h,32,rmask,gmask,bmask,amask);
SDL_Surface * car = TTF_RenderGlyph_Blended(font,ch,color);
SDL_Rect glyphRect = {0, 0, 100, 100};
SDL_Rect carRect = {100, 0, 300, 300};
PHDEBUG << SDL_BlitSurface(car, NULL, glyph, &glyphRect);
PHDEBUG << SDL_BlitSurface(glyph, NULL, screen, &glyphRect);