package com.android.launcher3.folder;
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public class ClippedFolderIconLayoutRule {
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public static final int MAX_NUM_ITEMS_IN_PREVIEW = 4;
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private static final int MIN_NUM_ITEMS_IN_PREVIEW = 2;
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private static final float MIN_SCALE = 0.48f;
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private static final float MAX_SCALE = 0.58f;
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private static final float MAX_RADIUS_DILATION = 0.15f;
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private static final float ITEM_RADIUS_SCALE_FACTOR = 1.33f;
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public static final int EXIT_INDEX = -2;
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public static final int ENTER_INDEX = -3;
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private float[] mTmpPoint = new float[2];
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private float mAvailableSpace;
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private float mRadius;
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private float mIconSize;
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private boolean mIsRtl;
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private float mBaselineIconScale;
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public void init(int availableSpace, float intrinsicIconSize, boolean rtl) {
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mAvailableSpace = availableSpace;
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mRadius = ITEM_RADIUS_SCALE_FACTOR * availableSpace / 2f;
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mIconSize = intrinsicIconSize;
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mIsRtl = rtl;
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mBaselineIconScale = availableSpace / (intrinsicIconSize * 1f);
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}
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public PreviewItemDrawingParams computePreviewItemDrawingParams(int index, int curNumItems,
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PreviewItemDrawingParams params) {
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float totalScale = scaleForItem(curNumItems);
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float transX;
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float transY;
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float overlayAlpha = 0;
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if (index == EXIT_INDEX) {
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// 0 1 * <-- Exit position (row 0, col 2)
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// 2 3
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getGridPosition(0, 2, mTmpPoint);
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} else if (index == ENTER_INDEX) {
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// 0 1
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// 2 3 * <-- Enter position (row 1, col 2)
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getGridPosition(1, 2, mTmpPoint);
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} else if (index >= MAX_NUM_ITEMS_IN_PREVIEW) {
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// Items beyond those displayed in the preview are animated to the center
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mTmpPoint[0] = mTmpPoint[1] = mAvailableSpace / 2 - (mIconSize * totalScale) / 2;
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} else {
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getPosition(index, curNumItems, mTmpPoint);
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}
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transX = mTmpPoint[0];
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transY = mTmpPoint[1];
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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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/**
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* Builds a grid based on the positioning of the items when there are
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* {@link #MAX_NUM_ITEMS_IN_PREVIEW} in the preview.
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*
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* Positions in the grid: 0 1 // 0 is row 0, col 1
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* 2 3 // 3 is row 1, col 1
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*/
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private void getGridPosition(int row, int col, float[] result) {
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// We use position 0 and 3 to calculate the x and y distances between items.
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getPosition(0, 4, result);
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float left = result[0];
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float top = result[1];
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getPosition(3, 4, result);
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float dx = result[0] - left;
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float dy = result[1] - top;
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result[0] = left + (col * dx);
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result[1] = top + (row * dy);
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}
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private void getPosition(int index, int curNumItems, float[] result) {
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// The case of two items is homomorphic to the case of one.
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curNumItems = Math.max(curNumItems, 2);
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// We model the preview as a circle of items starting in the appropriate piece of the
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// upper left quadrant (to achieve horizontal and vertical symmetry).
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double theta0 = mIsRtl ? 0 : Math.PI;
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// In RTL we go counterclockwise
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int direction = mIsRtl ? 1 : -1;
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double thetaShift = 0;
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if (curNumItems == 3) {
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thetaShift = Math.PI / 6;
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} else if (curNumItems == 4) {
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thetaShift = Math.PI / 4;
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}
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theta0 += direction * thetaShift;
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// We want the items to appear in reading order. For the case of 1, 2 and 3 items, this
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// is natural for the circular model. With 4 items, however, we need to swap the 3rd and
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// 4th indices to achieve reading order.
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if (curNumItems == 4 && index == 3) {
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index = 2;
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} else if (curNumItems == 4 && index == 2) {
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index = 3;
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}
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// We bump the radius up between 0 and MAX_RADIUS_DILATION % as the number of items increase
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float radius = mRadius * (1 + MAX_RADIUS_DILATION * (curNumItems -
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MIN_NUM_ITEMS_IN_PREVIEW) / (MAX_NUM_ITEMS_IN_PREVIEW - MIN_NUM_ITEMS_IN_PREVIEW));
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double theta = theta0 + index * (2 * Math.PI / curNumItems) * direction;
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float halfIconSize = (mIconSize * scaleForItem(curNumItems)) / 2;
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// Map the location along the circle, and offset the coordinates to represent the center
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// of the icon, and to be based from the top / left of the preview area. The y component
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// is inverted to match the coordinate system.
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result[0] = mAvailableSpace / 2 + (float) (radius * Math.cos(theta) / 2) - halfIconSize;
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result[1] = mAvailableSpace / 2 + (float) (- radius * Math.sin(theta) / 2) - halfIconSize;
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}
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public float scaleForItem(int numItems) {
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// Scale is determined by the number of items in the preview.
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final float scale;
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if (numItems <= 2) {
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scale = MAX_SCALE;
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} else if (numItems == 3) {
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scale = (MAX_SCALE + MIN_SCALE) / 2;
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} else {
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scale = MIN_SCALE;
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}
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return scale * mBaselineIconScale;
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}
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public float getIconSize() {
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return mIconSize;
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}
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}
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