changing the intensity of lighten/darken on bitmaps using PorterDuffXfermode in the Android Paint class

问题

Ok my orignal question has changed. How do i change the intensity of how something like this is effected?

    DayToNight.setXfermode(new PorterDuffXfermode(Mode.DST_IN));

in my dream world it would have worked like this

    DayToNight.setXfermode(new PorterDuffXfermode(Mode.DST_IN(10)));

the 10 being a level of intensity.

An example would be if I had a flickering candle, when the candle burns bright I want the bitmaps I am drawing to the screen to retain their origanol color and brightness, when it flickers I want the bitmaps to be almost blacked out, and I want to darken the Bitmaps as the light dims.

I have equations, timers and all that figured out, just not how to actually apply it to change the color/brightness. Maybe burning the images is what im looking for? I just want to change the lightness lol.

I feel like using paint.setShader might be a solution, but the information in this area is pretty limited from what i have been able to find. Any help would be appreciated.

edit: to be crystal clear, i am looking for a way to lighten/darken bitmaps as I draw them to the canvas

回答1:

These two approaches may solve your problem:

Put a dark rectangle behind your bitmap and set the Bitmap's opacity.
Use ColorFilter on your Paint when you draw the bitmap. To darken your bitmap use a semi-transparent black color

回答2:

Hey I have used a kind of trick to remove the black line.In my erase button, I have set the color to white, instead of using XferMode.. It works and looks good..

if(erase){
paintColor = Color.parseColor(newColor);
drawPaint.setColor(paintColor);
}

来源：https://stackoverflow.com/questions/11174583/changing-the-intensity-of-lighten-darken-on-bitmaps-using-porterduffxfermode-in

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java

android

graphics

shader

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