Android Open Source - yammp Touch Paint View

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Back to project page yammp.
License

The source code is released under:
GNU Lesser General Public License
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Java Source Code

package org.yammp.view;
/* w  w  w  .  j  a v a  2s . c om*/
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BlurMaskFilter;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PorterDuff.Mode;
import android.graphics.Rect;
import android.os.Handler;
import android.os.Message;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class TouchPaintView extends View {

  private static final int FADE_DELAY = 2;

  private static final int FADE_ALPHA = 0x10;
  private static final int MAX_FADE_STEPS = 256 / FADE_ALPHA * 2 + 8;
  private Bitmap mBitmap;
  private Canvas mCanvas;
  private Rect mRect = new Rect();
  private Paint mPaint;
  private boolean mCurDown;
  private int mCurX;
  private int mCurY;
  private float mCurSize;
  private int mCurWidth;
  private int mFadeSteps = 0;
  private int mColor = Color.WHITE;
  private EventListener mListener;

  private Handler mHandler = new Handler() {

    @Override
    public void handleMessage(Message msg) {
      mHandler.removeCallbacksAndMessages(null);
      if (mFadeSteps < MAX_FADE_STEPS) {
        fade();
        mHandler.sendEmptyMessageDelayed(0, FADE_DELAY);
      } else {
        mFadeSteps = 0;
      }
    }
  };

  public TouchPaintView(Context c) {
    super(c);
    init();
  }

  public TouchPaintView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
    if (mListener != null) {
      mListener.onTouchEvent(event);
    }
    int action = event.getAction();
    mCurDown = action == MotionEvent.ACTION_DOWN || action == MotionEvent.ACTION_MOVE;
    // int N = event.getHistorySize();
    // for (int i = 0; i < N; i++) {
    // drawPoint(event.getHistoricalX(i), event.getHistoricalY(i),
    // event.getHistoricalPressure(i), event.getHistoricalSize(i));
    // }
    drawPoint(event.getX(), event.getY(), event.getPressure(), event.getSize());
    mFadeSteps = 0;
    mHandler.sendEmptyMessageDelayed(0, FADE_DELAY);
    return true;
  }

  @Override
  public boolean onTrackballEvent(MotionEvent event) {
    if (mListener != null) {
      mListener.onTrackballEvent(event);
    }
    boolean oldDown = mCurDown;
    mCurDown = true;
    int N = event.getHistorySize();
    int baseX = mCurX;
    int baseY = mCurY;
    final float scaleX = event.getXPrecision();
    final float scaleY = event.getYPrecision();
    for (int i = 0; i < N; i++) {
      drawPoint(baseX + event.getHistoricalX(i) * scaleX, baseY + event.getHistoricalY(i)
          * scaleY, event.getHistoricalPressure(i), event.getHistoricalSize(i));
    }
    drawPoint(baseX + event.getX() * scaleX, baseY + event.getY() * scaleY,
        event.getPressure(), event.getSize());
    mCurDown = oldDown;
    mFadeSteps = 0;
    mHandler.sendEmptyMessageDelayed(0, FADE_DELAY);
    return true;
  }

  public void setColor(int color) {
    mColor = color;
  }

  public void setEventListener(EventListener listener) {
    mListener = listener;
  }

  private void drawPoint(float x, float y, float pressure, float size) {
    mCurX = (int) x;
    mCurY = (int) y;
    mCurSize = size;
    mCurWidth = (int) (mCurSize * 128);
    if (mCurWidth < 1) {
      mCurWidth = 1;
    }
    if (mCurDown && mBitmap != null) {
      int pressureLevel = (int) (Math.sqrt(pressure) * 128);
      mPaint.setARGB(pressureLevel, Color.red(mColor), Color.green(mColor),
          Color.blue(mColor));
      mPaint.setMaskFilter(new BlurMaskFilter(mCurWidth / 2, BlurMaskFilter.Blur.NORMAL));
      mCanvas.drawCircle(mCurX, mCurY, mCurWidth, mPaint);
      mRect.set(mCurX - mCurWidth - 2, mCurY - mCurWidth - 2, mCurX + mCurWidth + 2, mCurY
          + mCurWidth + 2);
      invalidate(mRect);
    }
    mFadeSteps = 0;
  }

  private void fade() {
    if (mCanvas != null && mFadeSteps < MAX_FADE_STEPS) {
      mCanvas.drawColor(Color.argb(FADE_ALPHA, 0xFF, 0xFF, 0xFF), Mode.DST_OUT);
      invalidate();
      mFadeSteps++;
    } else if (mFadeSteps >= MAX_FADE_STEPS) {
      mFadeSteps = 0;
      mHandler.removeCallbacksAndMessages(null);
    }
  }

  private void init() {
    setFocusable(true);

    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setColor(Color.TRANSPARENT);
  }

  @Override
  protected void onDraw(Canvas canvas) {
    if (mBitmap != null) {
      canvas.drawBitmap(mBitmap, 0, 0, null);
    }
  }

  @Override
  protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    int curW = mBitmap != null ? mBitmap.getWidth() : 0;
    int curH = mBitmap != null ? mBitmap.getHeight() : 0;
    if (curW >= w && curH >= h) return;

    if (curW < w) {
      curW = w;
    }
    if (curH < h) {
      curH = h;
    }

    Bitmap newBitmap = Bitmap.createBitmap(curW, curH, Bitmap.Config.ARGB_8888);
    Canvas newCanvas = new Canvas();
    newCanvas.setBitmap(newBitmap);
    if (mBitmap != null) {
      newCanvas.drawBitmap(mBitmap, 0, 0, null);
    }
    mBitmap = newBitmap;
    mCanvas = newCanvas;
    mFadeSteps = MAX_FADE_STEPS;
  }

  public interface EventListener {

    boolean onTouchEvent(MotionEvent event);

    boolean onTrackballEvent(MotionEvent event);
  }
}
Java Source Code List
