How can I replace specific color(RGB value) in CGBitmapContext
that has already drawn?
Is there any easy way?
Thanks in advance.
You'll want to get a pointer to the pixels and information about their format by doing something like this:
// This assumes the data is RGBA format, 8-bits per channel.
// You'll need to verify that by calling CGBitmapContextGetBitsPerPixel (), etc.
typedef struct RGBA8 {
UInt8 red;
UInt8 green;
UInt8 blue;
UInt8 alpha;
} RGBA8;
RGBA8* pixels = CGBitmapContextGetData (context);
UInt32 height = CGBitmapContextGetHeight (context);
UInt32 width = CGBitmapContextGetWidth (context);
UInt32 rowBytes = CGBitmapContextGetBytesPerRow (context);
UInt32 x, y;
for (y = 0; y < height; y++)
{
RGBA8* currentRow = (RGBA8*)((UInt8*)pixels + y * rowBytes);
for (x = 0; x < width; x++)
{
if ((currentRow->red == replaceRed) && (currentRow->green == replaceGreen) &&
(currentRow->blue == replaceBlue) && (currentRow->alpha == replaceAlpha))
{
currentRow->red = newRed;
currentRow->green = newGreen;
currentRow->blue = newBlue;
currentRow->alpha = newAlpha;
}
currentRow++;
}
}