WinAPI WC_LISTVIEW paint issues - c++

Question

I created a ListView using CreateWindowEx and using the WC_LISTVIEW as class name.
I'm trying to create a smooth scrolling. Everything works perfectly except that list is not drawn correctly. See below the screenshot of the list:
The list view has the following style in CreateWindowEx:
WS_CHILD | WS_VISIBLE | LVS_REPORT | LVS_NOCOLUMNHEADER |
WS_TABSTOP | WS_BORDER | LVS_SHOWSELALWAYS | LVS_SINGLESEL | LVS_OWNERDRAWFIXED
I'm using a timer to scroll window. It does the following:
ScrollWindowEx(
listHandle,
0,
step * linesDelta,
NULL,
NULL,
0, 0, 0
);
UpdateWindow(listHandle);
Scroll works perfectly except painting.
I tried:
UpdateWindow() - screenshoot attached
RedrawWindow with all possible options - window is painted only once
InvalidateRect + UpdateWindow = same as 2
InvalidateRect + SendMessage(hwnd, WM_PAINT, 0, 0) - same as 2
The code that paints the item for the list is below:
LRESULT drawItem(HWND hwnd, DRAWITEMSTRUCT* drawStruct) {
Item *itemData = (Item *)drawStruct->itemData;
HDC hdc = drawStruct->hDC;
COLORREF backgroundColor;
COLORREF oldColor;
if (drawStruct->itemState & ODS_SELECTED || ListView_GetHotItem(hwnd) == drawStruct->itemID) {
backgroundColor = GetSysColor(COLOR_HIGHLIGHT);
oldColor = SetTextColor(hdc, GetSysColor(COLOR_HIGHLIGHTTEXT));
} else {
backgroundColor = RGB(255, 255, 255);
oldColor = SetTextColor(hdc, GetSysColor(COLOR_CAPTIONTEXT));
}
HBRUSH backgroundBrush = CreateSolidBrush(backgroundColor);
HBRUSH hOldBrush = (HBRUSH)SelectObject(hdc, backgroundBrush);
FillRect(hdc, &drawStruct->rcItem, backgroundBrush);
drawStruct->rcItem.left += 5;
drawStruct->rcItem.right -= 5;
drawStruct->rcItem.left += 30;
DrawText(hdc, itemData->path, -1, &drawStruct->rcItem,
DT_NOPREFIX | DT_SINGLELINE | DT_END_ELLIPSIS);
drawStruct->rcItem.left -= 30;
if (itemData->searchData && itemData->searchData->bitmap) {
HBITMAP bitmap = itemData->searchData->bitmap;
HDC hdcMem = CreateCompatibleDC(hdc);
HGDIOBJ oldBitmap = SelectObject(hdcMem, bitmap);
BITMAPINFO bi = { 0 };
bi.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
// Get the bitmap info header.
if (0 != GetDIBits(
hdcMem, // hdc
bitmap, // hbmp
0, // uStartScan
0, // cScanLines
NULL, // lpvBits
&bi,
DIB_RGB_COLORS
)) {
BLENDFUNCTION blendFunc;
blendFunc.BlendOp = AC_SRC_OVER;
blendFunc.BlendFlags = 0;
blendFunc.SourceConstantAlpha = 255;
blendFunc.AlphaFormat = AC_SRC_ALPHA;
AlphaBlend(hdc,
drawStruct->rcItem.left + 2, //dest X
drawStruct->rcItem.top + 3, //dest Y
bi.bmiHeader.biWidth,
bi.bmiHeader.biHeight,
hdcMem, 0, 0,
bi.bmiHeader.biWidth,
bi.bmiHeader.biHeight, blendFunc);
}
SelectObject(hdcMem, oldBitmap);
DeleteDC(hdcMem);
}
SelectObject(hdc, hOldBrush);
DeleteObject(backgroundBrush);
SetTextColor(hdc, oldColor);
return 0;
}
Does anyone know a solution for this?
Please see below a complete example created from scratch that has exactly the same behavior:
#include "stdafx.h"
#include "TestList.h"
#include <strsafe.h>
#include <commctrl.h>
#define MAX_LOADSTRING 100
#define ID_LIST_BOX 200
#define TIMER_ID_SMOOTH_SCROLL 100
class ListData {
int scrollToDelta;
int currentScrollPos;
int numPixelsToChangeScrollPos;
int numPixelsChanged;
public:
HWND listWindow;
WNDPROC defaultListProcedure;
void startSmoothScrolling(HWND hwnd, int delta) {
if (delta < 0) {
scrollToDelta = 100;
} else {
scrollToDelta = -100;
}
SCROLLINFO si;
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_POS;
if (GetScrollInfo(listWindow, SB_VERT, &si)) {
double count = SendMessage(listWindow, LVM_GETITEMCOUNT, 0, 0);
double totalHeight = count * 30;
currentScrollPos = (int)((totalHeight * (double)si.nPos) / (double)si.nMax);
numPixelsToChangeScrollPos = totalHeight / si.nMax;
numPixelsChanged = 0;
} else {
currentScrollPos = 0;
numPixelsChanged = 0;
numPixelsToChangeScrollPos = 30;
}
}
void smoothScroll(HWND listHandle) {
SCROLLINFO si;
si.cbSize = sizeof(si);
si.fMask = SIF_RANGE | SIF_POS;
DWORD linesDelta;
SystemParametersInfo(SPI_GETWHEELSCROLLLINES, 0, &linesDelta, 0);
if (scrollToDelta < 0) {
if (GetScrollInfo(listHandle, SB_VERT, &si)) {
if (si.nPos == 0) {
KillTimer(listHandle, TIMER_ID_SMOOTH_SCROLL);
return;
}
}
scrollToDelta += 5;
int step = -5;
if (scrollToDelta > -80) {
step = -4;
} else if (scrollToDelta > -60) {
step = -3;
} else if (scrollToDelta > -40) {
step = -3;
} else if (scrollToDelta > -20) {
step = -2;
}
numPixelsChanged += abs(step);
if (numPixelsChanged >= numPixelsToChangeScrollPos) {
int posDelta = numPixelsChanged / numPixelsToChangeScrollPos;
numPixelsChanged -= posDelta * numPixelsToChangeScrollPos;
si.nPos = si.nPos + posDelta;
si.fMask = SIF_POS;
SetScrollInfo(listHandle, SB_VERT, &si, TRUE);
}
ScrollWindowEx(
listHandle,
0,
step * linesDelta,
NULL,
NULL,
0, 0,
SW_INVALIDATE);
if (scrollToDelta >= 0) {
KillTimer(listHandle, TIMER_ID_SMOOTH_SCROLL);
}
} else {
if (GetScrollInfo(listHandle, SB_VERT, &si)) {
int pos = GetScrollPos(listHandle, SB_VERT);
if (pos == si.nMax) {
KillTimer(listHandle, TIMER_ID_SMOOTH_SCROLL);
return;
}
}
scrollToDelta -= 5;
int step = 5;
if (scrollToDelta > -80) {
step = 4;
} else if (scrollToDelta > -60) {
step = 3;
} else if (scrollToDelta > -40) {
step = 3;
} else if (scrollToDelta > -20) {
step = 2;
}
numPixelsChanged += abs(step);
if (numPixelsChanged >= numPixelsToChangeScrollPos) {
int posDelta = numPixelsChanged / numPixelsToChangeScrollPos;
numPixelsChanged -= posDelta * numPixelsToChangeScrollPos;
si.nPos = si.nPos - posDelta;
si.fMask = SIF_POS;
SetScrollInfo(listHandle, SB_VERT, &si, TRUE);
}
ScrollWindowEx(
listHandle,
0,
step * linesDelta,
NULL,
NULL,
0, 0, 0
);
if (scrollToDelta <= 0) {
KillTimer(listHandle, TIMER_ID_SMOOTH_SCROLL);
}
}
////////////////////////////////////////////////////////////////////////////////////////////////////
//RedrawWindow(listHandle, NULL, NULL,
// RDW_UPDATENOW | RDW_INTERNALPAINT | RDW_INVALIDATE | RDW_NOERASE | RDW_ALLCHILDREN | RDW_ERASENOW);
//InvalidateRect(listHandle, NULL, FALSE);
//SendMessage(listHandle, WM_PAINT, 0, 0);
UpdateWindow(listHandle);
//ListView_RedrawItems(listHandle, 0, 300);
////////////////////////////////////////////////////////////////////////////////////////////////////
}
};
struct Item {
WCHAR *name;
};
// Global Variables:
HINSTANCE hInst; // current instance
WCHAR szTitle[MAX_LOADSTRING]; // The title bar text
WCHAR szWindowClass[MAX_LOADSTRING]; // the main window class name
// Forward declarations of functions included in this code module:
ATOM MyRegisterClass(HINSTANCE hInstance);
BOOL InitInstance(HINSTANCE, int);
LRESULT CALLBACK WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK About(HWND, UINT, WPARAM, LPARAM);
int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
_In_opt_ HINSTANCE hPrevInstance,
_In_ LPWSTR lpCmdLine,
_In_ int nCmdShow)
{
UNREFERENCED_PARAMETER(hPrevInstance);
UNREFERENCED_PARAMETER(lpCmdLine);
// TODO: Place code here.
// Initialize global strings
StringCchCopy(szTitle, MAX_LOADSTRING, L"Test");
StringCchCopy(szWindowClass, MAX_LOADSTRING, L"TestClassList");
MyRegisterClass(hInstance);
// Perform application initialization:
if (!InitInstance (hInstance, nCmdShow))
{
return FALSE;
}
HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_TESTLIST));
MSG msg;
// Main message loop:
while (GetMessage(&msg, nullptr, 0, 0))
{
if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
{
TranslateMessage(&msg);
DispatchMessage(&msg);
}
}
return (int) msg.wParam;
}
//
// FUNCTION: MyRegisterClass()
//
// PURPOSE: Registers the window class.
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
WNDCLASSEXW wcex;
wcex.cbSize = sizeof(WNDCLASSEX);
wcex.style = CS_HREDRAW | CS_VREDRAW;
wcex.lpfnWndProc = WndProc;
wcex.cbClsExtra = 0;
wcex.cbWndExtra = 0;
wcex.hInstance = hInstance;
wcex.hIcon = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_TESTLIST));
wcex.hCursor = LoadCursor(nullptr, IDC_ARROW);
wcex.hbrBackground = (HBRUSH)(COLOR_WINDOW+1);
wcex.lpszMenuName = MAKEINTRESOURCEW(IDC_TESTLIST);
wcex.lpszClassName = szWindowClass;
wcex.hIconSm = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));
return RegisterClassExW(&wcex);
}
LRESULT drawItem(HWND hwnd, DRAWITEMSTRUCT* drawStruct) {
Item *itemData = (Item *)drawStruct->itemData;
HDC hdc = drawStruct->hDC;
COLORREF backgroundColor;
//pcd->clrTextBk;
COLORREF oldColor;
if (drawStruct->itemState & ODS_SELECTED || ListView_GetHotItem(hwnd) == drawStruct->itemID) {
backgroundColor = GetSysColor(COLOR_HIGHLIGHT);
oldColor = SetTextColor(hdc, GetSysColor(COLOR_HIGHLIGHTTEXT));
} else {
backgroundColor = RGB(255, 255, 255);
oldColor = SetTextColor(hdc, GetSysColor(COLOR_CAPTIONTEXT));
}
HBRUSH backgroundBrush = CreateSolidBrush(backgroundColor);
HBRUSH hOldBrush = (HBRUSH)SelectObject(hdc, backgroundBrush);
FillRect(hdc, &drawStruct->rcItem, backgroundBrush);
drawStruct->rcItem.left += 5;
drawStruct->rcItem.right -= 5;
drawStruct->rcItem.left += 30;
DrawText(hdc, itemData->name, -1, &drawStruct->rcItem,
DT_NOPREFIX | DT_SINGLELINE | DT_END_ELLIPSIS);
drawStruct->rcItem.left -= 30;
SelectObject(hdc, hOldBrush);
DeleteObject(backgroundBrush);
SetTextColor(hdc, oldColor);
return 0;
}
LRESULT CALLBACK ListViewWindowProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam) {
switch (uMsg) {
////////////////////////////////////////////////////////////////////////////////////////////////////
case WM_TIMER: {
if (wParam == TIMER_ID_SMOOTH_SCROLL) {
ListData *listData = (ListData*)GetWindowLongPtr(hwnd, GWLP_USERDATA);
listData->smoothScroll(hwnd);
}
break;
}
case WM_MOUSEWHEEL: {
int delta = HIWORD(wParam);
ListData *listData = (ListData*)GetWindowLongPtr(hwnd, GWLP_USERDATA);
listData->startSmoothScrolling(hwnd, delta);
SetTimer(hwnd, TIMER_ID_SMOOTH_SCROLL, 200, NULL);
}
////////////////////////////////////////////////////////////////////////////////////////////////////
default:
ListData *listData = (ListData*)GetWindowLongPtr(hwnd, GWLP_USERDATA);
return CallWindowProc(listData->defaultListProcedure, hwnd, uMsg, wParam, lParam);
}
return 0;
}
//
// FUNCTION: InitInstance(HINSTANCE, int)
//
// PURPOSE: Saves instance handle and creates main window
//
// COMMENTS:
//
// In this function, we save the instance handle in a global variable and
// create and display the main program window.
//
BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
hInst = hInstance; // Store instance handle in our global variable
HWND hWnd = CreateWindowW(szWindowClass, szTitle, WS_OVERLAPPEDWINDOW,
100, 100, 400, 400, nullptr, nullptr, hInstance, nullptr);
if (!hWnd) {
return FALSE;
}
////////////////////////////////////////////////////////////////////////////////////////////////////
HWND listWindow = CreateWindowEx(
0,
WC_LISTVIEW,
L"",
WS_CHILD | WS_VISIBLE | LVS_REPORT | LVS_NOCOLUMNHEADER |
WS_TABSTOP | WS_BORDER | LVS_SHOWSELALWAYS | LVS_SINGLESEL | LVS_OWNERDRAWFIXED,
1, //x
1, //y
400 - 20, //width
400 - 20, //height
hWnd,
(HMENU)ID_LIST_BOX,
hInstance,
NULL);
ListData *listData = new ListData();
listData->listWindow = listWindow;
SetWindowLongPtr(listWindow, GWLP_USERDATA, (LPARAM)listData);
listData->defaultListProcedure = (WNDPROC)SetWindowLongPtr(listWindow, GWLP_WNDPROC, (LONG_PTR)ListViewWindowProc);
ListView_SetExtendedListViewStyle(listWindow, LVS_EX_FULLROWSELECT | LVS_EX_DOUBLEBUFFER | LVS_EX_AUTOSIZECOLUMNS);
SendMessage(listWindow, LVM_SETTEXTBKCOLOR, 0, 0xFFFFFF);
LVCOLUMN col;
col.mask = LVCF_TEXT | LVCF_WIDTH;
col.pszText = L"";
col.cx = 390;
SendMessage(listWindow, LVM_INSERTCOLUMN, 0, (LPARAM)&col);
LVITEM item;
item.mask = LVIF_PARAM | LVIF_TEXT;
item.iSubItem = 0;
for (int i = 0; i < 300; i++) {
item.iItem = i;
Item *itemData = (Item*)malloc(sizeof(Item));
WCHAR *name = (WCHAR*)malloc(sizeof(WCHAR) * 30);;
wsprintf(name, L"Item Name %d", i);
itemData->name = name;
item.pszText = name;
item.lParam = (LPARAM)itemData;
SendMessage(listWindow, LVM_INSERTITEM, 0, (LPARAM)&item);
}
////////////////////////////////////////////////////////////////////////////////////////////////////
ShowWindow(hWnd, nCmdShow);
UpdateWindow(hWnd);
return TRUE;
}
//
// FUNCTION: WndProc(HWND, UINT, WPARAM, LPARAM)
//
// PURPOSE: Processes messages for the main window.
//
// WM_COMMAND - process the application menu
// WM_PAINT - Paint the main window
// WM_DESTROY - post a quit message and return
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
switch (message) {
case WM_DRAWITEM: {
////////////////////////////////////////////////////////////////////////////////////////////////////
if (wParam == ID_LIST_BOX) {
DRAWITEMSTRUCT *drawStruct = (DRAWITEMSTRUCT*)lParam;
drawItem(drawStruct->hwndItem, drawStruct);
return TRUE;
}
////////////////////////////////////////////////////////////////////////////////////////////////////
break;
}
case WM_PAINT: {
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
// TODO: Add any drawing code that uses hdc here...
EndPaint(hWnd, &ps);
}
break;
case WM_MEASUREITEM: {
if (wParam == ID_LIST_BOX) {
MEASUREITEMSTRUCT *measureStruct = (MEASUREITEMSTRUCT*)lParam;
measureStruct->itemHeight = 30;
measureStruct->itemWidth = 390;
return TRUE;
}
break;
}
case WM_DESTROY:
PostQuitMessage(0);
break;
default:
return DefWindowProc(hWnd, message, wParam, lParam);
}
return 0;
}

Answer 1

Here's an old trick: before invoking ScrollWindowEx() invalidate the entire listHandle area without erasing the background.
InvalidateRect(listHandle, NULL, FALSE);
ScrollWindowEx(...
Have a nice day!

Answer 2

From MSDN for ScrollWindowEx:
If the SW_INVALIDATE and SW_ERASE flags are not specified, ScrollWindowEx does not invalidate the area that is scrolled from. If either of these flags is set, ScrollWindowEx invalidates this area. The area is not updated until the application calls the UpdateWindow function, calls the RedrawWindow function (specifying the RDW_UPDATENOW or RDW_ERASENOW flag), or retrieves the WM_PAINT message from the application queue.
So let's look at what you tried:
UpdateWindow() - screenshoot attached
Nothing got invalidated, so the update region is empty, so UpdateWindow does nothing.
RedrawWindow with all possible options - window is painted only once
If called correctly, this should invalidate the client. You can cause the WM_ERASEBKGND to happen immediately, but the WM_PAINT message will come only when there's nothing else in the queue. I suspect this didn't work because the WM_TIMER takes priority over the WM_PAINT. (Both are special messages in that they are not actually posted but synthesized when you call GetMessage and nothing else is pending.)
InvalidateRect + UpdateWindow = same as 2
I would expect this to work, but it seems to make more sense to pass the flags to ScrollWindowEx to get the invalidation. I think what's happening is that the control is not designed to draw the items an non-integral positions. So you're getting invalidation, but the window is attempting to draw the items at different offsets than you expect. I don't see an straightforward way to solve this.
InvalidateRect + SendMessage(hwnd, WM_PAINT, 0, 0) - same as 2
That's not a valid WM_PAINT message. Don't do that.

Answer 3

The problem is that ListView is created using the LVS_REPORT flag. This means that list cannot scroll smoothly but only in lines. I.e. if line height is, for instance, 25, scrolling 20 pixels will make the list scroll 25 pixels.
One more issue is that ScrollWindowEx doesn't really scroll the list (or at least it wasn't used correctly). In order to scroll the list, the ListView_Scroll macro should be used (which again scrolls by lines not by pixels).