Adam Cohen
4f8071b759
-> Tracking individual drawing parms for each item -> This enables animation of the preview items as the preview changes Change-Id: I1b8f650cb28dc09cfb921bbdc93f2a3db61178fd
92 lines
3.4 KiB
Java
92 lines
3.4 KiB
Java
/**
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* Copyright (C) 2015 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.launcher3.folder;
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import android.graphics.Path;
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import com.android.launcher3.folder.FolderIcon.PreviewItemDrawingParams;
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public class StackFolderIconLayoutRule implements FolderIcon.PreviewLayoutRule {
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static final int MAX_NUM_ITEMS_IN_PREVIEW = 3;
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// The degree to which the item in the back of the stack is scaled [0...1]
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// (0 means it's not scaled at all, 1 means it's scaled to nothing)
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private static final float PERSPECTIVE_SCALE_FACTOR = 0.35f;
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// The amount of vertical spread between items in the stack [0...1]
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private static final float PERSPECTIVE_SHIFT_FACTOR = 0.18f;
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private float mBaselineIconScale;
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private int mBaselineIconSize;
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private int mAvailableSpaceInPreview;
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private float mMaxPerspectiveShift;
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@Override
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public void init(int availableSpace, int intrinsicIconSize, boolean rtl) {
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mAvailableSpaceInPreview = availableSpace;
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// cos(45) = 0.707 + ~= 0.1) = 0.8f
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int adjustedAvailableSpace = (int) ((mAvailableSpaceInPreview / 2) * (1 + 0.8f));
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int unscaledHeight = (int) (intrinsicIconSize * (1 + PERSPECTIVE_SHIFT_FACTOR));
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mBaselineIconScale = (1.0f * adjustedAvailableSpace / unscaledHeight);
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mBaselineIconSize = (int) (intrinsicIconSize * mBaselineIconScale);
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mMaxPerspectiveShift = mBaselineIconSize * PERSPECTIVE_SHIFT_FACTOR;
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}
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@Override
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public PreviewItemDrawingParams computePreviewItemDrawingParams(int index, int curNumItems,
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PreviewItemDrawingParams params) {
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index = MAX_NUM_ITEMS_IN_PREVIEW - index - 1;
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float r = (index * 1.0f) / (MAX_NUM_ITEMS_IN_PREVIEW - 1);
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float scale = (1 - PERSPECTIVE_SCALE_FACTOR * (1 - r));
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float offset = (1 - r) * mMaxPerspectiveShift;
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float scaledSize = scale * mBaselineIconSize;
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float scaleOffsetCorrection = (1 - scale) * mBaselineIconSize;
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// We want to imagine our coordinates from the bottom left, growing up and to the
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// right. This is natural for the x-axis, but for the y-axis, we have to invert things.
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float transY = mAvailableSpaceInPreview - (offset + scaledSize + scaleOffsetCorrection);
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float transX = (mAvailableSpaceInPreview - scaledSize) / 2;
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float totalScale = mBaselineIconScale * scale;
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final float overlayAlpha = (80 * (1 - r)) / 255f;
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if (params == null) {
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params = new PreviewItemDrawingParams(transX, transY, totalScale, overlayAlpha);
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} else {
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params.update(transX, transY, totalScale);
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params.overlayAlpha = overlayAlpha;
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}
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return params;
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}
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@Override
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public int numItems() {
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return MAX_NUM_ITEMS_IN_PREVIEW;
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}
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@Override
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public Path getClipPath() {
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return null;
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}
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}
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