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/*
* Copyright (C) 2011 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.android.gallery3d.ui;
import com.android.gallery3d.R;
import com.android.gallery3d.common.Utils;
import android.content.Context;
import android.view.GestureDetector;
import android.view.MotionEvent;
import android.view.View.MeasureSpec;
// The current implementation can only scroll vertically.
public class ScrollView extends GLView {
private static final int MIN_SCROLLER_HEIGHT = 20;
private NinePatchTexture mScroller;
private int mScrollLimit = 0;
private int mScrollerHeight = MIN_SCROLLER_HEIGHT;
private GestureDetector mGestureDetector;
public ScrollView(Context context) {
mScroller = new NinePatchTexture(context, R.drawable.scrollbar_handle_holo_dark);
mGestureDetector = new GestureDetector(context, new MyGestureListener());
}
private GLView getContentView() {
return getComponentCount() == 0 ? null : getComponent(0);
}
@Override
public void onLayout(boolean sizeChange, int l, int t, int r, int b) {
GLView content = getContentView();
int width = getWidth();
int height = getHeight();
content.measure(MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY),
MeasureSpec.UNSPECIFIED);
int contentHeight = content.getMeasuredHeight();
content.layout(0, 0, width, contentHeight);
if (height < contentHeight) {
mScrollLimit = contentHeight - height;
mScrollerHeight = Math.max(MIN_SCROLLER_HEIGHT,
height * height / contentHeight);
} else {
mScrollLimit = 0;
}
mScrollY = Utils.clamp(mScrollY, 0, mScrollLimit);
}
@Override
public void render(GLCanvas canvas) {
GLView content = getContentView();
if (content == null) return;
int width = getWidth();
int height = getHeight();
canvas.save(GLCanvas.SAVE_FLAG_CLIP);
canvas.clipRect(0, 0, width, height);
super.render(canvas);
if (mScrollLimit > 0) {
int x = getWidth() - mScroller.getWidth();
int y = (height - mScrollerHeight) * mScrollY / mScrollLimit;
mScroller.draw(canvas, x, y, mScroller.getWidth(), mScrollerHeight);
}
canvas.restore();
}
@Override
public boolean onTouch(MotionEvent event) {
mGestureDetector.onTouchEvent(event);
return true;
}
private class MyGestureListener
extends GestureDetector.SimpleOnGestureListener {
@Override
public boolean onScroll(MotionEvent e1,
MotionEvent e2, float distanceX, float distanceY) {
mScrollY = Utils.clamp(mScrollY + (int) distanceY, 0, mScrollLimit);
invalidate();
return true;
}
}
}
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