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/*
* Copyright 2012 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 com.example.android.animationsdemo;
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.widget.ImageButton;
/**
* An image button that uses a blue highlight (@link android.R.attr.selectableItemBackground} to
* indicate pressed and focused states.
*/
public class TouchHighlightImageButton extends ImageButton {
/**
* The highlight drawable. This generally a {@link android.graphics.drawable.StateListDrawable}
* that's transparent in the default state, and contains a semi-transparent overlay
* for the focused and pressed states.
*/
private Drawable mForegroundDrawable;
/**
* The cached bounds of the view.
*/
private Rect mCachedBounds = new Rect();
public TouchHighlightImageButton(Context context) {
super(context);
init();
}
public TouchHighlightImageButton(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public TouchHighlightImageButton(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
init();
}
/**
* General view initialization used common to all constructors of the view.
*/
private void init() {
// Reset default ImageButton background and padding.
setBackgroundColor(0);
setPadding(0, 0, 0, 0);
// Retrieve the drawable resource assigned to the android.R.attr.selectableItemBackground
// theme attribute from the current theme.
TypedArray a = getContext()
.obtainStyledAttributes(new int[]{android.R.attr.selectableItemBackground});
mForegroundDrawable = a.getDrawable(0);
mForegroundDrawable.setCallback(this);
a.recycle();
}
@Override
protected void drawableStateChanged() {
super.drawableStateChanged();
// Update the state of the highlight drawable to match
// the state of the button.
if (mForegroundDrawable.isStateful()) {
mForegroundDrawable.setState(getDrawableState());
}
// Trigger a redraw.
invalidate();
}
@Override
protected void onDraw(Canvas canvas) {
// First draw the image.
super.onDraw(canvas);
// Then draw the highlight on top of it. If the button is neither focused
// nor pressed, the drawable will be transparent, so just the image
// will be drawn.
mForegroundDrawable.setBounds(mCachedBounds);
mForegroundDrawable.draw(canvas);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
// Cache the view bounds.
mCachedBounds.set(0, 0, w, h);
}
}
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