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| #define FILL_STYLE_VERTICAL 0
#define FILL_STYLE_HORIZONTAL 1
void fillGradientRect(HDC hdc, RECT *rc, COLORREF fromRGB, COLORREF toRGB, int fillStyle)
{
BITMAPINFO bmpInfo;
memset(&bmpInfo, 0, sizeof(bmpInfo));
bmpInfo.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
bmpInfo.bmiHeader.biWidth = rc->right - rc->left;
bmpInfo.bmiHeader.biHeight = rc->bottom - rc->top;
bmpInfo.bmiHeader.biPlanes = 1;
bmpInfo.bmiHeader.biBitCount = 32;
bmpInfo.bmiHeader.biCompression = BI_RGB;
BYTE *rgbBuffer = (BYTE *)malloc(bmpInfo.bmiHeader.biWidth * bmpInfo.bmiHeader.biHeight * 4);
int width = bmpInfo.bmiHeader.biWidth;
int height = bmpInfo.bmiHeader.biHeight;
int rStart = fromRGB & 0xFF;
int rEnd = toRGB & 0xFF;
int gStart = (fromRGB & 0xFF00) >> 8;
int gEnd = (toRGB & 0xFF00) >> 8;
int bStart = (fromRGB & 0xFF0000) >> 16;
int bEnd = (toRGB & 0xFF0000) >> 16;
if (FILL_STYLE_VERTICAL == fillStyle)
{
double rStep = (rEnd - rStart) * 1.0 / height;
double gStep = (gEnd - gStart) * 1.0 / height;
double bStep = (bEnd - bStart) * 1.0 / height;
for (int y = 0; y < height; y++)
{
BYTE r = (BYTE)(rStart + rStep * y);
BYTE g = (BYTE)(gStart + gStep * y);
BYTE b = (BYTE)(bStart + bStep * y);
for (int x = 0; x < width; x++)
{
BYTE *p = rgbBuffer + ((height - y) * width - (width - x)) * 4;
*p++ = b;
*p++ = g;
*p++ = r;
}
}
}
else
{
double rStep = (rEnd - rStart) * 1.0 / width;
double gStep = (gEnd - gStart) * 1.0 / width;
double bStep = (bEnd - bStart) * 1.0 / width;
for (int x = 0; x < width; x++)
{
BYTE r = (BYTE)(rStart + rStep * x);
BYTE g = (BYTE)(gStart + gStep * x);
BYTE b = (BYTE)(bStart + bStep * x);
for (int y = 0; y < height; y++)
{
BYTE *p = rgbBuffer + ((height - y) * width - (width - x)) * 4;
*p++ = b;
*p++ = g;
*p++ = r;
}
}
}
StretchDIBits(hdc, rc->left, rc->top, width, height, 0, 0, width, height, rgbBuffer, &bmpInfo, DIB_RGB_COLORS, SRCCOPY);
free(rgbBuffer);
}
void CMFCApplicationDlg::OnPaint()
{
CPaintDC dc(this);
CRect rc(50, 50, 200, 200);
fillGradientRect(dc.m_hDC, rc, RGB(255, 0, 255), RGB(0, 255, 0), FILL_STYLE_HORIZONTAL);
CDialogEx::OnPaint();
} |