Function hBitmapFromImage

bitmap.go:523–568

(im image.Image, dpi int)

}

func hBitmapFromImage(im image.Image, dpi int) (win.HBITMAP, error) {
	var bi win.BITMAPV5HEADER
	bi.BiSize = uint32(unsafe.Sizeof(bi))
	bi.BiWidth = int32(im.Bounds().Dx())
	bi.BiHeight = -int32(im.Bounds().Dy())
	bi.BiPlanes = 1
	bi.BiBitCount = 32
	bi.BiCompression = win.BI_BITFIELDS
	dpm := int32(math.Round(float64(dpi) * inchesPerMeter))
	bi.BiXPelsPerMeter = dpm
	bi.BiYPelsPerMeter = dpm
	// The following mask specification specifies a supported 32 BPP
	// alpha format for Windows XP.
	bi.BV4RedMask = 0x00FF0000
	bi.BV4GreenMask = 0x0000FF00
	bi.BV4BlueMask = 0x000000FF
	bi.BV4AlphaMask = 0xFF000000

	hdc := win.GetDC(0)
	defer win.ReleaseDC(0, hdc)

	var lpBits unsafe.Pointer

	// Create the DIB section with an alpha channel.
	hBitmap := win.CreateDIBSection(hdc, &bi.BITMAPINFOHEADER, win.DIB_RGB_COLORS, &lpBits, 0, 0)
	switch hBitmap {
	case 0, win.ERROR_INVALID_PARAMETER:
		return 0, newError("CreateDIBSection failed")
	}

	// Fill the image
	bitmap_array := (*[1 << 30]byte)(unsafe.Pointer(lpBits))
	i := 0
	for y := im.Bounds().Min.Y; y != im.Bounds().Max.Y; y++ {
		for x := im.Bounds().Min.X; x != im.Bounds().Max.X; x++ {
			r, g, b, a := im.At(x, y).RGBA()
			bitmap_array[i+3] = byte(a >> 8)
			bitmap_array[i+2] = byte(r >> 8)
			bitmap_array[i+1] = byte(g >> 8)
			bitmap_array[i+0] = byte(b >> 8)
			i += 4
		}
	}

	return hBitmap, nil
}

func hBitmapFromWindow(window Window) (win.HBITMAP, error) {
	hdcMem := win.CreateCompatibleDC(0)