Android Open Source - Sketcher Alpha Picker

From Project

Back to project page Sketcher.

License

The source code is released under:

Apache License

If you think the Android project Sketcher listed in this page is inappropriate, such as containing malicious code/tools or violating the copyright, please email info at java2s dot com, thanks.

Java Source Code

package org.sketcher.colorpicker;
//from  w w  w  .j av a2 s .  c om
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Paint.Style;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.Shader.TileMode;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class AlphaPicker extends View implements Picker {
  private static final float PICKER_RADIUS = 4;

  private Picker.OnColorChangedListener mListener = null;
  private final Paint mColor = new Paint();
  private float[] mHsv = new float[3];
  private final Paint mGradient = new Paint(Paint.ANTI_ALIAS_FLAG);
  private final Paint mTrackerPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

  public AlphaPicker(Context context, AttributeSet attrs) {
    super(context, attrs);
    mGradient.setStyle(Paint.Style.STROKE);

    mTrackerPaint.setStrokeWidth(1);
    mTrackerPaint.setColor(Color.WHITE);
    mTrackerPaint.setStyle(Style.STROKE);
  }

  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);

    applyChages(w, h);
  }

  @Override
  public void setColor(int color) {
    mColor.setColor(color);

    mHsv = Utils.color2HSV(color);

    applyChages(getWidth(), getHeight());
  }

  private void applyChages(int w, int h) {
    int color = Color.HSVToColor(255, mHsv);
    int acolor = Color.HSVToColor(0, mHsv);

    Shader alphaShader = new LinearGradient(0, 0, w, 0, color, acolor,
        TileMode.CLAMP);

    mGradient.setShader(alphaShader);
    mGradient.setStrokeWidth(h);
    invalidate();
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
    case MotionEvent.ACTION_MOVE:
      float x = Math.max(0, Math.min(getWidth(), event.getX()));
      int alpha = (int) ((1f - x / getWidth()) * 255f);
      mColor.setColor(Color.HSVToColor(alpha, mHsv));

      mListener.colorChanged(mColor);
      invalidate();
      return true;
    }

    return false;
  }

  @Override
  public void setOnColorChangedListener(OnColorChangedListener listener) {
    mListener = listener;
  }

  @Override
  protected void onDraw(Canvas canvas) {
    canvas.drawRect(0, PICKER_RADIUS, getWidth(), getHeight()
        - PICKER_RADIUS, mGradient);

    float x = (1f - mColor.getAlpha() / 255f) * getWidth();

    RectF rect = new RectF();
    rect.left = x - PICKER_RADIUS;
    rect.right = x + PICKER_RADIUS;
    rect.top = 0;
    rect.bottom = getHeight();

    canvas.drawRoundRect(rect, PICKER_RADIUS, PICKER_RADIUS, mTrackerPaint);
  }
}

Java Source Code List