image.setDrawingAlpha()
Sets the current drawing alpha for images. All subsequent graphics operations use the specified alpha.
image.setDrawingAlpha( alpha=number )
Returns: Image
Examples
img=imageNew("", 250, 250, "RGB", "a29bfe");
img.setDrawingAlpha(0.3);
img.drawRect(50, 50, 50, 50);
img.setDrawingAlpha(0.6);
img.drawRect(75, 75, 75, 75);
img.setDrawingAlpha(1);
img.drawRect(100, 100, 100, 100);
writeOutput(img);