CODEWITHSUNDEEP
androidandroid-canvasdrawpixel
Dmytro Zarezenko
Dmytro Zarezenko

Reputation: 10686

Android canvas change some pixels color

I have a Canvas object at start. I need to change color of some pixels depending on their current color. How can I do that in a proper way?

Details:

I have my own class extended from ImageView. In onDraw(Canvas canvas) method I draw something with third party class and have only Canvas object with result. I need after that change color of some pixels depending on their current color.

Upvotes: 8

Views: 13005

Answers (3)

Aman J
Aman J

Reputation: 1855

Assuming that you have android.graphics.Canvas object called canvas and X & Y are points where you want to change pixel, so here you go

Call :

canvas.drawPoint(X, Y, paint);

Here is how you initalize Object of class android.graphics.Paint i.e paint

Paint paint = new Paint();
paint.setStyle(Paint.Style.FILL);
paint.setColor(Color.WHITE);

Search more on this Link to change multiple pixels at different positions, there are lot many functions that will help you achieve what you want. Best luck :-)

Upvotes: 4

hBrent
hBrent

Reputation: 1716

I recommend looking at Faster way to set a (PNG) bitmap color instead of pixel by pixel. It has code to get and set bitmap colors pixel by pixel (in the question), as well as a suggestion for an alternative to a pixel by pixel approach (in the answer). Also possibly useful: Explanation of the method getPixels for a Bitmap in Android.

Upvotes: 0

Joe Plante
Joe Plante

Reputation: 6368

There's probably a dozen ways to do this. If you want to do the Canvas approach, there's a way to draw to a Bitmap object. You can then draw the object to another Canvas. The Bitmap object may also have functions to modify pixels.

Bitmap also lets you get a copy into a buffer, and if you know about how pixels are stored, that would be a very fast way of image manipulation. I'm not sure if Canvas itself has that

Upvotes: 0

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