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/**
* Copyright (C) 2015 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.launcher3.folder;
import android.view.View;
import com.android.launcher3.folder.FolderIcon.PreviewItemDrawingParams;
import java.util.List;
public class StackFolderIconLayoutRule implements FolderIcon.PreviewLayoutRule {
static final int MAX_NUM_ITEMS_IN_PREVIEW = 3;
// The degree to which the item in the back of the stack is scaled [0...1]
// (0 means it's not scaled at all, 1 means it's scaled to nothing)
private static final float PERSPECTIVE_SCALE_FACTOR = 0.35f;
// The amount of vertical spread between items in the stack [0...1]
private static final float PERSPECTIVE_SHIFT_FACTOR = 0.18f;
private float mBaselineIconScale;
private int mBaselineIconSize;
private int mAvailableSpaceInPreview;
private float mMaxPerspectiveShift;
@Override
public void init(int availableSpace, int intrinsicIconSize, boolean rtl) {
mAvailableSpaceInPreview = availableSpace;
// cos(45) = 0.707 + ~= 0.1) = 0.8f
int adjustedAvailableSpace = (int) ((mAvailableSpaceInPreview / 2) * (1 + 0.8f));
int unscaledHeight = (int) (intrinsicIconSize * (1 + PERSPECTIVE_SHIFT_FACTOR));
mBaselineIconScale = (1.0f * adjustedAvailableSpace / unscaledHeight);
mBaselineIconSize = (int) (intrinsicIconSize * mBaselineIconScale);
mMaxPerspectiveShift = mBaselineIconSize * PERSPECTIVE_SHIFT_FACTOR;
}
@Override
public PreviewItemDrawingParams computePreviewItemDrawingParams(int index, int curNumItems,
PreviewItemDrawingParams params) {
float scale = scaleForItem(index, curNumItems);
index = MAX_NUM_ITEMS_IN_PREVIEW - index - 1;
float r = (index * 1.0f) / (MAX_NUM_ITEMS_IN_PREVIEW - 1);
float offset = (1 - r) * mMaxPerspectiveShift;
float scaledSize = scale * mBaselineIconSize;
float scaleOffsetCorrection = (1 - scale) * mBaselineIconSize;
// We want to imagine our coordinates from the bottom left, growing up and to the
// right. This is natural for the x-axis, but for the y-axis, we have to invert things.
float transY = mAvailableSpaceInPreview - (offset + scaledSize + scaleOffsetCorrection);
float transX = (mAvailableSpaceInPreview - scaledSize) / 2;
float totalScale = mBaselineIconScale * scale;
final float overlayAlpha = (80 * (1 - r)) / 255f;
if (params == null) {
params = new PreviewItemDrawingParams(transX, transY, totalScale, overlayAlpha);
} else {
params.update(transX, transY, totalScale);
params.overlayAlpha = overlayAlpha;
}
return params;
}
@Override
public int maxNumItems() {
return MAX_NUM_ITEMS_IN_PREVIEW;
}
@Override
public float getIconSize() {
return mBaselineIconSize;
}
@Override
public float scaleForItem(int index, int numItems) {
// Scale is determined by the position of the icon in the preview.
index = MAX_NUM_ITEMS_IN_PREVIEW - index - 1;
float r = (index * 1.0f) / (MAX_NUM_ITEMS_IN_PREVIEW - 1);
return (1 - PERSPECTIVE_SCALE_FACTOR * (1 - r));
}
@Override
public boolean clipToBackground() {
return false;
}
}
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