src/android/src/com/google/android/inputmethod/japanese/view/BaseBackgroundDrawable.java

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package org.mozc.android.inputmethod.japanese.view;

import android.graphics.ColorFilter;
import android.graphics.PixelFormat;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;

/**
 * The basic implementation which is shared by drawables for background.
 *
 * Currently this class supports padding related stuff.
 */
abstract class BaseBackgroundDrawable extends Drawable {
  private final int leftPadding;
  private final int topPadding;
  private final int rightPadding;
  private final int bottomPadding;

  private Rect canvasRect = new Rect();

  BaseBackgroundDrawable(int leftPadding, int topPadding, int rightPadding, int bottomPadding) {
    this.leftPadding = leftPadding;
    this.topPadding = topPadding;
    this.rightPadding = rightPadding;
    this.bottomPadding = bottomPadding;
  }

  @Override
  protected void onBoundsChange(Rect bounds) {
    super.onBoundsChange(bounds);
    canvasRect.set(bounds.left + leftPadding,
                   bounds.top + topPadding,
                   bounds.right - rightPadding,
                   bounds.bottom - bottomPadding);
  }

  protected boolean isCanvasRectEmpty() {
    return canvasRect.isEmpty();
  }

  /**
   * @return the region without padding.
   */
  protected Rect getCanvasRect() {
    return new Rect(canvasRect);
  }

  /** Supporting alpha channel. */
  @Override
  public int getOpacity() {
    return PixelFormat.TRANSLUCENT;
  }

  @Override
  public void setAlpha(int alpha) {
    // Do nothing.
  }

  @Override
  public void setColorFilter(ColorFilter cf) {
    // Do nothing.
  }
}