Signal-Android/src/org/thoughtcrime/securesms/components/ForegroundImageView.java

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.thoughtcrime.securesms.components;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.util.AttributeSet;
import android.view.Gravity;
import android.widget.ImageView;

import org.thoughtcrime.securesms.R;

/**
 * https://gist.github.com/chrisbanes/9091754
 */
public class ForegroundImageView extends ImageView {

  private Drawable mForeground;

  private final Rect mSelfBounds = new Rect();
  private final Rect mOverlayBounds = new Rect();

  private int mForegroundGravity = Gravity.FILL;

  protected boolean mForegroundInPadding = true;

  boolean mForegroundBoundsChanged = false;

  public ForegroundImageView(Context context) {
    super(context);
  }

  public ForegroundImageView(Context context, AttributeSet attrs) {
    this(context, attrs, 0);
  }

  public ForegroundImageView(Context context, AttributeSet attrs, int defStyle) {
    super(context, attrs, defStyle);

    TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.ForegroundImageView,
      defStyle, 0);

    mForegroundGravity = a.getInt(
      R.styleable.ForegroundImageView_android_foregroundGravity, mForegroundGravity);

    final Drawable d = a.getDrawable(R.styleable.ForegroundImageView_android_foreground);
    if (d != null) {
      setForeground(d);
    }

    mForegroundInPadding = a.getBoolean(
      R.styleable.ForegroundImageView_android_foregroundInsidePadding, true);

    a.recycle();
  }

  /**
   * Describes how the foreground is positioned.
   *
   * @return foreground gravity.
   *
   * @see #setForegroundGravity(int)
   */
  public int getForegroundGravity() {
    return mForegroundGravity;
  }

  /**
   * Describes how the foreground is positioned. Defaults to START and TOP.
   *
   * @param foregroundGravity See {@link android.view.Gravity}
   *
   * @see #getForegroundGravity()
   */
  public void setForegroundGravity(int foregroundGravity) {
    if (mForegroundGravity != foregroundGravity) {
      if ((foregroundGravity & Gravity.RELATIVE_HORIZONTAL_GRAVITY_MASK) == 0) {
        foregroundGravity |= Gravity.START;
      }

      if ((foregroundGravity & Gravity.VERTICAL_GRAVITY_MASK) == 0) {
        foregroundGravity |= Gravity.TOP;
      }

      mForegroundGravity = foregroundGravity;


      if (mForegroundGravity == Gravity.FILL && mForeground != null) {
        Rect padding = new Rect();
        mForeground.getPadding(padding);
      }

      requestLayout();
    }
  }

  @Override
  protected boolean verifyDrawable(Drawable who) {
    return super.verifyDrawable(who) || (who == mForeground);
  }

  @Override
  public void jumpDrawablesToCurrentState() {
    super.jumpDrawablesToCurrentState();
    if (mForeground != null) mForeground.jumpToCurrentState();
  }

  @Override
  protected void drawableStateChanged() {
    super.drawableStateChanged();
    if (mForeground != null && mForeground.isStateful()) {
      mForeground.setState(getDrawableState());
    }
  }

  /**
   * Supply a Drawable that is to be rendered on top of all of the child
   * views in the frame layout.  Any padding in the Drawable will be taken
   * into account by ensuring that the children are inset to be placed
   * inside of the padding area.
   *
   * @param drawable The Drawable to be drawn on top of the children.
   */
  public void setForeground(Drawable drawable) {
    if (mForeground != drawable) {
      if (mForeground != null) {
        mForeground.setCallback(null);
        unscheduleDrawable(mForeground);
      }

      mForeground = drawable;

      if (drawable != null) {
        setWillNotDraw(false);
        drawable.setCallback(this);
        if (drawable.isStateful()) {
          drawable.setState(getDrawableState());
        }
        if (mForegroundGravity == Gravity.FILL) {
          Rect padding = new Rect();
          drawable.getPadding(padding);
        }
      }  else {
        setWillNotDraw(true);
      }
      requestLayout();
      invalidate();
    }
  }

  /**
   * Returns the drawable used as the foreground of this FrameLayout. The
   * foreground drawable, if non-null, is always drawn on top of the children.
   *
   * @return A Drawable or null if no foreground was set.
   */
  public Drawable getForeground() {
    return mForeground;
  }

  @Override
  protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
    super.onLayout(changed, left, top, right, bottom);
    mForegroundBoundsChanged = changed;
  }

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

  @Override
  public void draw(Canvas canvas) {
    super.draw(canvas);

    if (mForeground != null) {
      final Drawable foreground = mForeground;

      if (mForegroundBoundsChanged) {
        mForegroundBoundsChanged = false;
        final Rect selfBounds = mSelfBounds;
        final Rect overlayBounds = mOverlayBounds;

        final int w = getRight() - getLeft();
        final int h = getBottom() - getTop();

        if (mForegroundInPadding) {
          selfBounds.set(0, 0, w, h);
        } else {
          selfBounds.set(getPaddingLeft(), getPaddingTop(),
            w - getPaddingRight(), h - getPaddingBottom());
        }

        Gravity.apply(mForegroundGravity, foreground.getIntrinsicWidth(),
          foreground.getIntrinsicHeight(), selfBounds, overlayBounds);
        foreground.setBounds(overlayBounds);
      }

      foreground.draw(canvas);
    }
  }

}