src/com/android/launcher3/util/IconNormalizer.java - platform/packages/apps/Launcher3 - Git at Google

 /*
  * 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.util;

 import android.graphics.Bitmap;
 import android.graphics.Canvas;
 import android.graphics.Color;
 import android.graphics.RectF;
 import android.graphics.drawable.Drawable;

 import com.android.launcher3.LauncherAppState;

 import java.nio.ByteBuffer;

 public class IconNormalizer {

     // Ratio of icon visible area to full icon size for a square shaped icon
     private static final float MAX_SQUARE_AREA_FACTOR = 375.0f / 576;
     // Ratio of icon visible area to full icon size for a circular shaped icon
     private static final float MAX_CIRCLE_AREA_FACTOR = 380.0f / 576;

     private static final float CIRCLE_AREA_BY_RECT = (float) Math.PI / 4;

     // Slope used to calculate icon visible area to full icon size for any generic shaped icon.
     private static final float LINEAR_SCALE_SLOPE =
             (MAX_CIRCLE_AREA_FACTOR - MAX_SQUARE_AREA_FACTOR) / (1 - CIRCLE_AREA_BY_RECT);

     private static final int MIN_VISIBLE_ALPHA = 40;

     private static final Object LOCK = new Object();
     private static IconNormalizer sIconNormalizer;

     private final int mMaxSize;
     private final Bitmap mBitmap;
     private final Canvas mCanvas;
     private final byte[] mPixels;

     // for each y, stores the position of the leftmost x and the rightmost x
     private final float[] mLeftBorder;
     private final float[] mRightBorder;

     private IconNormalizer() {
         // Use twice the icon size as maximum size to avoid scaling down twice.
         mMaxSize = LauncherAppState.getInstance().getInvariantDeviceProfile().iconBitmapSize * 2;
         mBitmap = Bitmap.createBitmap(mMaxSize, mMaxSize, Bitmap.Config.ALPHA_8);
         mCanvas = new Canvas(mBitmap);
         mPixels = new byte[mMaxSize * mMaxSize];

         mLeftBorder = new float[mMaxSize];
         mRightBorder = new float[mMaxSize];
     }

     /**
      * Returns the amount by which the {@param d} should be scaled (in both dimensions) so that it
      * matches the design guidelines for a launcher icon.
      *
      * We first calculate the convex hull of the visible portion of the icon.
      * This hull then compared with the bounding rectangle of the hull to find how closely it
      * resembles a circle and a square, by comparing the ratio of the areas. Note that this is not an
      * ideal solution but it gives satisfactory result without affecting the performance.
      *
      * This closeness is used to determine the ratio of hull area to the full icon size.
      * Refer {@link #MAX_CIRCLE_AREA_FACTOR} and {@link #MAX_SQUARE_AREA_FACTOR}
      *
      * @param outBounds optional rect to receive the fraction distance from each edge.
      */
     public synchronized float getScale(Drawable d, RectF outBounds) {
         int width = d.getIntrinsicWidth();
         int height = d.getIntrinsicHeight();
         if (width <= 0 || height <= 0) {
             width = width <= 0 || width > mMaxSize ? mMaxSize : width;
             height = height <= 0 || height > mMaxSize ? mMaxSize : height;
         } else if (width > mMaxSize || height > mMaxSize) {
             int max = Math.max(width, height);
             width = mMaxSize * width / max;
             height = mMaxSize * height / max;
         }

         mBitmap.eraseColor(Color.TRANSPARENT);
         d.setBounds(0, 0, width, height);
         d.draw(mCanvas);

         ByteBuffer buffer = ByteBuffer.wrap(mPixels);
         buffer.rewind();
         mBitmap.copyPixelsToBuffer(buffer);

         // Overall bounds of the visible icon.
         int topY = -1;
         int bottomY = -1;
         int leftX = mMaxSize + 1;
         int rightX = -1;

         // Create border by going through all pixels one row at a time and for each row find
         // the first and the last non-transparent pixel. Set those values to mLeftBorder and
         // mRightBorder and use -1 if there are no visible pixel in the row.

         // buffer position
         int index = 0;
         // buffer shift after every row, width of buffer = mMaxSize
         int rowSizeDiff = mMaxSize - width;
         // first and last position for any row.
         int firstX, lastX;

         for (int y = 0; y < height; y++) {
             firstX = lastX = -1;
             for (int x = 0; x < width; x++) {
                 if ((mPixels[index] & 0xFF) > MIN_VISIBLE_ALPHA) {
                     if (firstX == -1) {
                         firstX = x;
                     }
                     lastX = x;
                 }
                 index++;
             }
             index += rowSizeDiff;

             mLeftBorder[y] = firstX;
             mRightBorder[y] = lastX;

             // If there is at least one visible pixel, update the overall bounds.
             if (firstX != -1) {
                 bottomY = y;
                 if (topY == -1) {
                     topY = y;
                 }

                 leftX = Math.min(leftX, firstX);
                 rightX = Math.max(rightX, lastX);
             }
         }

         if (topY == -1 || rightX == -1) {
             // No valid pixels found. Do not scale.
             return 1;
         }

         convertToConvexArray(mLeftBorder, 1, topY, bottomY);
         convertToConvexArray(mRightBorder, -1, topY, bottomY);

         // Area of the convex hull
         float area = 0;
         for (int y = 0; y < height; y++) {
             if (mLeftBorder[y] <= -1) {
                 continue;
             }
             area += mRightBorder[y] - mLeftBorder[y] + 1;
         }

         // Area of the rectangle required to fit the convex hull
         float rectArea = (bottomY + 1 - topY) * (rightX + 1 - leftX);
         float hullByRect = area / rectArea;

         float scaleRequired;
         if (hullByRect < CIRCLE_AREA_BY_RECT) {
             scaleRequired = MAX_CIRCLE_AREA_FACTOR;
         } else {
             scaleRequired = MAX_SQUARE_AREA_FACTOR + LINEAR_SCALE_SLOPE * (1  - hullByRect);
         }

         if (outBounds != null) {
             outBounds.left = ((float) leftX) / width;
             outBounds.right = 1 - ((float) rightX) / width;

             outBounds.top = ((float) topY) / height;
             outBounds.bottom = 1 - ((float) bottomY) / height;
         }

         float areaScale = area / (width * height);
         // Use sqrt of the final ratio as the images is scaled across both width and height.
         float scale = areaScale > scaleRequired ? (float) Math.sqrt(scaleRequired / areaScale) : 1;
         return scale;
     }

     /**
      * Modifies {@param xCordinates} to represent a convex border. Fills in all missing values
      * (except on either ends) with appropriate values.
      * @param xCordinates map of x coordinate per y.
      * @param direction 1 for left border and -1 for right border.
      * @param topY the first Y position (inclusive) with a valid value.
      * @param bottomY the last Y position (inclusive) with a valid value.
      */
     private static void convertToConvexArray(
             float[] xCordinates, int direction, int topY, int bottomY) {
         int total = xCordinates.length;
         // The tangent at each pixel.
         float[] angles = new float[total - 1];

         int first = topY; // First valid y coordinate
         int last = -1;    // Last valid y coordinate which didn't have a missing value

         float lastAngle = Float.MAX_VALUE;

         for (int i = topY + 1; i <= bottomY; i++) {
             if (xCordinates[i] <= -1) {
                 continue;
             }
             int start;

             if (lastAngle == Float.MAX_VALUE) {
                 start = first;
             } else {
                 float currentAngle = (xCordinates[i] - xCordinates[last]) / (i - last);
                 start = last;
                 // If this position creates a concave angle, keep moving up until we find a
                 // position which creates a convex angle.
                 if ((currentAngle - lastAngle) * direction < 0) {
                     while (start > first) {
                         start --;
                         currentAngle = (xCordinates[i] - xCordinates[start]) / (i - start);
                         if ((currentAngle - angles[start]) * direction >= 0) {
                             break;
                         }
                     }
                 }
             }

             // Reset from last check
             lastAngle = (xCordinates[i] - xCordinates[start]) / (i - start);
             // Update all the points from start.
             for (int j = start; j < i; j++) {
                 angles[j] = lastAngle;
                 xCordinates[j] = xCordinates[start] + lastAngle * (j - start);
             }
             last = i;
         }
     }

     public static IconNormalizer getInstance() {
         synchronized (LOCK) {
             if (sIconNormalizer == null) {
                 sIconNormalizer = new IconNormalizer();
             }
         }
         return sIconNormalizer;
     }
 }
	/*
	* 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.util;

	import android.graphics.Bitmap;
	import android.graphics.Canvas;
	import android.graphics.Color;
	import android.graphics.RectF;
	import android.graphics.drawable.Drawable;

	import com.android.launcher3.LauncherAppState;

	import java.nio.ByteBuffer;

	public class IconNormalizer {

	// Ratio of icon visible area to full icon size for a square shaped icon
	private static final float MAX_SQUARE_AREA_FACTOR = 375.0f / 576;
	// Ratio of icon visible area to full icon size for a circular shaped icon
	private static final float MAX_CIRCLE_AREA_FACTOR = 380.0f / 576;

	private static final float CIRCLE_AREA_BY_RECT = (float) Math.PI / 4;

	// Slope used to calculate icon visible area to full icon size for any generic shaped icon.
	private static final float LINEAR_SCALE_SLOPE =
	(MAX_CIRCLE_AREA_FACTOR - MAX_SQUARE_AREA_FACTOR) / (1 - CIRCLE_AREA_BY_RECT);

	private static final int MIN_VISIBLE_ALPHA = 40;

	private static final Object LOCK = new Object();
	private static IconNormalizer sIconNormalizer;

	private final int mMaxSize;
	private final Bitmap mBitmap;
	private final Canvas mCanvas;
	private final byte[] mPixels;

	// for each y, stores the position of the leftmost x and the rightmost x
	private final float[] mLeftBorder;
	private final float[] mRightBorder;

	private IconNormalizer() {
	// Use twice the icon size as maximum size to avoid scaling down twice.
	mMaxSize = LauncherAppState.getInstance().getInvariantDeviceProfile().iconBitmapSize * 2;
	mBitmap = Bitmap.createBitmap(mMaxSize, mMaxSize, Bitmap.Config.ALPHA_8);
	mCanvas = new Canvas(mBitmap);
	mPixels = new byte[mMaxSize * mMaxSize];

	mLeftBorder = new float[mMaxSize];
	mRightBorder = new float[mMaxSize];
	}

	/**
	* Returns the amount by which the {@param d} should be scaled (in both dimensions) so that it
	* matches the design guidelines for a launcher icon.
	*
	* We first calculate the convex hull of the visible portion of the icon.
	* This hull then compared with the bounding rectangle of the hull to find how closely it
	* resembles a circle and a square, by comparing the ratio of the areas. Note that this is not an
	* ideal solution but it gives satisfactory result without affecting the performance.
	*
	* This closeness is used to determine the ratio of hull area to the full icon size.
	* Refer {@link #MAX_CIRCLE_AREA_FACTOR} and {@link #MAX_SQUARE_AREA_FACTOR}
	*
	* @param outBounds optional rect to receive the fraction distance from each edge.
	*/
	public synchronized float getScale(Drawable d, RectF outBounds) {
	int width = d.getIntrinsicWidth();
	int height = d.getIntrinsicHeight();
	if (width <= 0 \|\| height <= 0) {
	width = width <= 0 \|\| width > mMaxSize ? mMaxSize : width;
	height = height <= 0 \|\| height > mMaxSize ? mMaxSize : height;
	} else if (width > mMaxSize \|\| height > mMaxSize) {
	int max = Math.max(width, height);
	width = mMaxSize * width / max;
	height = mMaxSize * height / max;
	}

	mBitmap.eraseColor(Color.TRANSPARENT);
	d.setBounds(0, 0, width, height);
	d.draw(mCanvas);

	ByteBuffer buffer = ByteBuffer.wrap(mPixels);
	buffer.rewind();
	mBitmap.copyPixelsToBuffer(buffer);

	// Overall bounds of the visible icon.
	int topY = -1;
	int bottomY = -1;
	int leftX = mMaxSize + 1;
	int rightX = -1;

	// Create border by going through all pixels one row at a time and for each row find
	// the first and the last non-transparent pixel. Set those values to mLeftBorder and
	// mRightBorder and use -1 if there are no visible pixel in the row.

	// buffer position
	int index = 0;
	// buffer shift after every row, width of buffer = mMaxSize
	int rowSizeDiff = mMaxSize - width;
	// first and last position for any row.
	int firstX, lastX;

	for (int y = 0; y < height; y++) {
	firstX = lastX = -1;
	for (int x = 0; x < width; x++) {
	if ((mPixels[index] & 0xFF) > MIN_VISIBLE_ALPHA) {
	if (firstX == -1) {
	firstX = x;
	}
	lastX = x;
	}
	index++;
	}
	index += rowSizeDiff;

	mLeftBorder[y] = firstX;
	mRightBorder[y] = lastX;

	// If there is at least one visible pixel, update the overall bounds.
	if (firstX != -1) {
	bottomY = y;
	if (topY == -1) {
	topY = y;
	}

	leftX = Math.min(leftX, firstX);
	rightX = Math.max(rightX, lastX);
	}
	}

	if (topY == -1 \|\| rightX == -1) {
	// No valid pixels found. Do not scale.
	return 1;
	}

	convertToConvexArray(mLeftBorder, 1, topY, bottomY);
	convertToConvexArray(mRightBorder, -1, topY, bottomY);

	// Area of the convex hull
	float area = 0;
	for (int y = 0; y < height; y++) {
	if (mLeftBorder[y] <= -1) {
	continue;
	}
	area += mRightBorder[y] - mLeftBorder[y] + 1;
	}

	// Area of the rectangle required to fit the convex hull
	float rectArea = (bottomY + 1 - topY) * (rightX + 1 - leftX);
	float hullByRect = area / rectArea;

	float scaleRequired;
	if (hullByRect < CIRCLE_AREA_BY_RECT) {
	scaleRequired = MAX_CIRCLE_AREA_FACTOR;
	} else {
	scaleRequired = MAX_SQUARE_AREA_FACTOR + LINEAR_SCALE_SLOPE * (1 - hullByRect);
	}

	if (outBounds != null) {
	outBounds.left = ((float) leftX) / width;
	outBounds.right = 1 - ((float) rightX) / width;

	outBounds.top = ((float) topY) / height;
	outBounds.bottom = 1 - ((float) bottomY) / height;
	}

	float areaScale = area / (width * height);
	// Use sqrt of the final ratio as the images is scaled across both width and height.
	float scale = areaScale > scaleRequired ? (float) Math.sqrt(scaleRequired / areaScale) : 1;
	return scale;
	}

	/**
	* Modifies {@param xCordinates} to represent a convex border. Fills in all missing values
	* (except on either ends) with appropriate values.
	* @param xCordinates map of x coordinate per y.
	* @param direction 1 for left border and -1 for right border.
	* @param topY the first Y position (inclusive) with a valid value.
	* @param bottomY the last Y position (inclusive) with a valid value.
	*/
	private static void convertToConvexArray(
	float[] xCordinates, int direction, int topY, int bottomY) {
	int total = xCordinates.length;
	// The tangent at each pixel.
	float[] angles = new float[total - 1];

	int first = topY; // First valid y coordinate
	int last = -1; // Last valid y coordinate which didn't have a missing value

	float lastAngle = Float.MAX_VALUE;

	for (int i = topY + 1; i <= bottomY; i++) {
	if (xCordinates[i] <= -1) {
	continue;
	}
	int start;

	if (lastAngle == Float.MAX_VALUE) {
	start = first;
	} else {
	float currentAngle = (xCordinates[i] - xCordinates[last]) / (i - last);
	start = last;
	// If this position creates a concave angle, keep moving up until we find a
	// position which creates a convex angle.
	if ((currentAngle - lastAngle) * direction < 0) {
	while (start > first) {
	start --;
	currentAngle = (xCordinates[i] - xCordinates[start]) / (i - start);
	if ((currentAngle - angles[start]) * direction >= 0) {
	break;
	}
	}
	}
	}

	// Reset from last check
	lastAngle = (xCordinates[i] - xCordinates[start]) / (i - start);
	// Update all the points from start.
	for (int j = start; j < i; j++) {
	angles[j] = lastAngle;
	xCordinates[j] = xCordinates[start] + lastAngle * (j - start);
	}
	last = i;
	}
	}

	public static IconNormalizer getInstance() {
	synchronized (LOCK) {
	if (sIconNormalizer == null) {
	sIconNormalizer = new IconNormalizer();
	}
	}
	return sIconNormalizer;
	}
	}