- 1 year ago
How to copy or reproduce the menu background gradient onto a bitmap using the Windows API?
To copy or reproduce the menu background gradient onto a bitmap using the Windows API, you can use the following steps:
Obtain the menu background gradient colors:
Use theGetSysColor
function to retrieve the system colors used for the menu background gradient. The relevant colors areCOLOR_MENU
andCOLOR_MENUHILIGHT
, which represent the start and end colors of the gradient, respectively.Create a compatible device context (DC) and bitmap:
Use theCreateCompatibleDC
function to create a compatible device context. Then, use theCreateCompatibleBitmap
function to create a bitmap of the desired size.Select the bitmap into the device context:
Use theSelectObject
function to select the created bitmap into the compatible device context.Draw the gradient onto the bitmap:
Use theGradientFill
function to draw the gradient onto the bitmap. Pass the device context, bitmap, and the gradient start and end colors obtained in Step 1.Clean up resources:
Release the device context and bitmap resources using theDeleteDC
andDeleteObject
functions, respectively.
Here's an example code snippet demonstrating these steps:
cpp#include <Windows.h>
void CopyMenuBackgroundGradient(HDC hdc, const RECT& rect)
{
// Obtain the menu background gradient colors
COLORREF startColor = GetSysColor(COLOR_MENU);
COLORREF endColor = GetSysColor(COLOR_MENUHILIGHT);
// Create a compatible device context
HDC hdcCompatible = CreateCompatibleDC(hdc);
// Create a bitmap
HBITMAP hBitmap = CreateCompatibleBitmap(hdc, rect.right - rect.left, rect.bottom - rect.top);
// Select the bitmap into the compatible device context
HBITMAP hBitmapOld = static_cast<HBITMAP>(SelectObject(hdcCompatible, hBitmap));
// Draw the gradient onto the bitmap
TRIVERTEX vertex[2] = { 0 };
vertex[0].x = rect.left;
vertex[0].y = rect.top;
vertex[0].Red = GetRValue(startColor) << 8;
vertex[0].Green = GetGValue(startColor) << 8;
vertex[0].Blue = GetBValue(startColor) << 8;
vertex[1].x = rect.right;
vertex[1].y = rect.bottom;
vertex[1].Red = GetRValue(endColor) << 8;
vertex[1].Green = GetGValue(endColor) << 8;
vertex[1].Blue = GetBValue(endColor) << 8;
GRADIENT_RECT gradientRect = { 0, 1 };
GradientFill(hdcCompatible, vertex, 2, &gradientRect, 1, GRADIENT_FILL_RECT_V);
// BitBlt the bitmap onto the target device context (hdc)
BitBlt(hdc, rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top, hdcCompatible, 0, 0, SRCCOPY);
// Clean up resources
SelectObject(hdcCompatible, hBitmapOld);
DeleteObject(hBitmap);
DeleteDC(hdcCompatible);
}
To use this function, pass the handle to the target device context (hdc
) and the rectangle specifying the area where you want to copy the menu background gradient.
Note that this code assumes you have the necessary Windows API headers included (#include <Windows.h>
) and that you are compiling with the appropriate libraries.