Color Choiser

totohh · by **totohh** » Tue May 04, 2010 9:50 am

Hi,

First of all I apologize for my English. I am a french developer.
I want to make a view that helps me to choose a color. A circle with all the color well know and after I listen the touch screen to calculate the color chosen.

I am suprised by the long running task of drawing : about 20 s, I think the use is not ready to wait so much time. I give you my code source.

Thx.
ToToHH

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package fr.android.colorpicker;
 
import android.content.Context;
 
import android.graphics.Canvas;
 
import android.graphics.Paint;
 
import android.graphics.PointF;
 
import android.util.Log;
 
import android.view.View;
 
public class CircleView extends View {
 
        private final static int WIDTH = 280;
 
        private final static int HEIGHT = 280;
 
        public CircleView(Context context) {
 
                super(context);
 
                this.setDrawingCacheEnabled(true);
 
        }
 
        private ARGB getRGBAAtPoint(PointF point) {
 
                long t = System.currentTimeMillis();
 
                float radius = CircleView.WIDTH / 2;
 
                float centreX = CircleView.WIDTH / 2;
 
                float centreY = CircleView.HEIGHT / 2;
 
                float deltaX = point.x - centreX;
 
                float deltaY = point.y - centreY;
 
                float distSquared = deltaX * deltaX + deltaY * deltaY;
 
                if (distSquared > radius * radius) {
 
                        return null;
 
                } else {
 
                        float dist = (float) Math.sqrt(distSquared);
 
                        float hue = (float) (Math.atan2(deltaY, deltaX) * 180.0f / Math.PI);
 
                        float saturation = dist / radius;
 
                        HSV hsv = new HSV(hue, saturation, 1);
 
                        float alpha = Math.abs(dist - radius) < 1.0f ? Math.abs(dist - radius) : 1.0f;
 
                        Log.i("CIRCLEVIEW_getRGBAAtPoint", "time to draw: " + (System.currentTimeMillis() - t) / 1000);
 
                        t = System.currentTimeMillis();
 
                        ARGB argb = new ARGB(alpha, hsv.toRGB());
 
                        Log.i("CIRCLEVIEW_hsv.toRGB", "time to draw: " + (System.currentTimeMillis() - t) / 1000);
 
                        return argb;
 
                }
 
        }
 
        @Override
 
        public void draw(Canvas canvas) {
 
                // super.draw(canvas);
 
                long t = System.currentTimeMillis();
 
                for (int x = 0; x < CircleView.WIDTH; x++) {
 
                        for (int y = 0; y < CircleView.HEIGHT; y++) {
 
                                ARGB argb = this.getRGBAAtPoint(new PointF((float) x, (float) y));
 
                                if (argb != null) {
 
                                        int color = ((int) (argb.getAlpha() * 255.f) << 24)
 
                                                        | ((int) (argb.getRGB().getB() * 255.f) << 16)
 
                                                        | ((int) (argb.getRGB().getG() * 255.f) << <img src="http://www.anddev.org/images/smilies/cool.png" alt="8)" title="Cool" />
 
                                                        | ((int) (argb.getRGB().getR() * 255.f));
 
                                        Paint paint = new Paint();
 
                                        paint.setColor(color);
 
                                        canvas.drawPoint((float)x, (float)y, paint);
 
                                }
 
                        }
 
                }
 
                Log.i("CIRCLEVIEW_DRAW", "time to draw: " + (System.currentTimeMillis() - t) / 1000);
 
        }
 
}
 
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MichaelEGR · by **MichaelEGR** » Tue May 04, 2010 4:51 pm

Hi.. This can be made more efficient. Right off the bat be very mindful of creating new objects in Java especially in processing loops.

Also you can draw the image once into a Bitmap and simply redraw the Bitmap in the "onDraw" method of your View. You should use "onDraw" instead of "draw" also don't forget to call super.onDraw(canvas).

totohh · by **totohh** » Tue May 04, 2010 7:16 pm

MichaelEGR wrote:Also you can draw the image once into a Bitmap...

Thx for your answer. I've also already test this java code but same result.
Maybe I've made a mistake ...

I think it is because I instantiate too much objects. So I've tried this morning to do that with int[] arrays but nevertheless my view takes about 10s to be loaded. What can I do please ?

Color Choiser

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