android/setupwizardlib/GlifPatternDrawable.java

/*
 * 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.setupwizardlib;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ColorFilter;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.os.Build;
import androidx.annotation.NonNull;
import androidx.annotation.VisibleForTesting;
import java.lang.ref.SoftReference;

/**
 * This class draws the GLIF pattern used as the status bar background for phones and background for
 * tablets in GLIF layout.
 */
public class GlifPatternDrawable extends Drawable {
  /*
   * This class essentially implements a simple SVG in Java code, with some special handling of
   * scaling when given different bounds.
   */

  /* static section */

  @SuppressLint("InlinedApi")
  private static final int[] ATTRS_PRIMARY_COLOR = new int[] {android.R.attr.colorPrimary};

  private static final float VIEWBOX_HEIGHT = 768f;
  private static final float VIEWBOX_WIDTH = 1366f;
  // X coordinate of scale focus, as a fraction of the width. (Range is 0 - 1)
  private static final float SCALE_FOCUS_X = .146f;
  // Y coordinate of scale focus, as a fraction of the height. (Range is 0 - 1)
  private static final float SCALE_FOCUS_Y = .228f;

  // Alpha component of the color to be drawn, on top of the grayscale pattern. (Range is 0 - 1)
  private static final float COLOR_ALPHA = .8f;
  // Int version of COLOR_ALPHA. (Range is 0 - 255)
  private static final int COLOR_ALPHA_INT = (int) (COLOR_ALPHA * 255);

  // Cap the bitmap size, such that it won't hurt the performance too much
  // and it won't crash due to a very large scale.
  // The drawable will look blurry above this size.
  // This is a multiplier applied on top of the viewbox size.
  // Resulting max cache size = (1.5 x 1366, 1.5 x 768) = (2049, 1152)
  private static final float MAX_CACHED_BITMAP_SCALE = 1.5f;

  private static final int NUM_PATHS = 7;

  private static SoftReference<Bitmap> bitmapCache;
  private static Path[] patternPaths;
  private static int[] patternLightness;

  public static GlifPatternDrawable getDefault(Context context) {
    int colorPrimary = 0;
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
      final TypedArray a = context.obtainStyledAttributes(ATTRS_PRIMARY_COLOR);
      colorPrimary = a.getColor(0, Color.BLACK);
      a.recycle();
    }
    return new GlifPatternDrawable(colorPrimary);
  }

  @VisibleForTesting
  public static void invalidatePattern() {
    bitmapCache = null;
  }

  /* non-static section */

  private int color;
  private final Paint tempPaint = new Paint(Paint.ANTI_ALIAS_FLAG);

  public GlifPatternDrawable(int color) {
    setColor(color);
  }

  @Override
  public void draw(@NonNull Canvas canvas) {
    final Rect bounds = getBounds();
    int drawableWidth = bounds.width();
    int drawableHeight = bounds.height();
    Bitmap bitmap = null;
    if (bitmapCache != null) {
      bitmap = bitmapCache.get();
    }
    if (bitmap != null) {
      final int bitmapWidth = bitmap.getWidth();
      final int bitmapHeight = bitmap.getHeight();
      // Invalidate the cache if this drawable is bigger and we can still create a bigger
      // cache.
      if (drawableWidth > bitmapWidth && bitmapWidth < VIEWBOX_WIDTH * MAX_CACHED_BITMAP_SCALE) {
        bitmap = null;
      } else if (drawableHeight > bitmapHeight
          && bitmapHeight < VIEWBOX_HEIGHT * MAX_CACHED_BITMAP_SCALE) {
        bitmap = null;
      }
    }

    if (bitmap == null) {
      // Reset the paint so it can be used to draw the paths in renderOnCanvas
      tempPaint.reset();

      bitmap = createBitmapCache(drawableWidth, drawableHeight);
      bitmapCache = new SoftReference<>(bitmap);

      // Reset the paint to so it can be used to draw the bitmap
      tempPaint.reset();
    }

    canvas.save();
    canvas.clipRect(bounds);

    scaleCanvasToBounds(canvas, bitmap, bounds);
    canvas.drawColor(Color.BLACK);
    tempPaint.setColor(Color.WHITE);
    canvas.drawBitmap(bitmap, 0, 0, tempPaint);
    canvas.drawColor(color);

    canvas.restore();
  }

  @VisibleForTesting
  public Bitmap createBitmapCache(int drawableWidth, int drawableHeight) {
    float scaleX = drawableWidth / VIEWBOX_WIDTH;
    float scaleY = drawableHeight / VIEWBOX_HEIGHT;
    float scale = Math.max(scaleX, scaleY);
    scale = Math.min(MAX_CACHED_BITMAP_SCALE, scale);

    int scaledWidth = (int) (VIEWBOX_WIDTH * scale);
    int scaledHeight = (int) (VIEWBOX_HEIGHT * scale);

    // Use ALPHA_8 mask to save memory, since the pattern is grayscale only anyway.
    Bitmap bitmap = Bitmap.createBitmap(scaledWidth, scaledHeight, Bitmap.Config.ALPHA_8);
    Canvas bitmapCanvas = new Canvas(bitmap);
    renderOnCanvas(bitmapCanvas, scale);
    return bitmap;
  }

  private void renderOnCanvas(Canvas canvas, float scale) {
    canvas.save();
    canvas.scale(scale, scale);

    tempPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));

    // Draw the pattern by creating the paths, adjusting the colors and drawing them. The path
    // values are extracted from the SVG of the pattern file.

    if (patternPaths == null) {
      patternPaths = new Path[NUM_PATHS];
      // Lightness values of the pattern, range 0 - 255
      patternLightness = new int[] {10, 40, 51, 66, 91, 112, 130};

      Path p = patternPaths[0] = new Path();
      p.moveTo(1029.4f, 357.5f);
      p.lineTo(1366f, 759.1f);
      p.lineTo(1366f, 0f);
      p.lineTo(1137.7f, 0f);
      p.close();

      p = patternPaths[1] = new Path();
      p.moveTo(1138.1f, 0f);
      p.rLineTo(-144.8f, 768f);
      p.rLineTo(372.7f, 0f);
      p.rLineTo(0f, -524f);
      p.cubicTo(1290.7f, 121.6f, 1219.2f, 41.1f, 1178.7f, 0f);
      p.close();

      p = patternPaths[2] = new Path();
      p.moveTo(949.8f, 768f);
      p.rCubicTo(92.6f, -170.6f, 213f, -440.3f, 269.4f, -768f);
      p.lineTo(585f, 0f);
      p.rLineTo(2.1f, 766f);
      p.close();

      p = patternPaths[3] = new Path();
      p.moveTo(471.1f, 768f);
      p.rMoveTo(704.5f, 0f);
      p.cubicTo(1123.6f, 563.3f, 1027.4f, 275.2f, 856.2f, 0f);
      p.lineTo(476.4f, 0f);
      p.rLineTo(-5.3f, 768f);
      p.close();

      p = patternPaths[4] = new Path();
      p.moveTo(323.1f, 768f);
      p.moveTo(777.5f, 768f);
      p.cubicTo(661.9f, 348.8f, 427.2f, 21.4f, 401.2f, 25.4f);
      p.lineTo(323.1f, 768f);
      p.close();

      p = patternPaths[5] = new Path();
      p.moveTo(178.44286f, 766.8571f);
      p.lineTo(308.7f, 768f);
      p.cubicTo(381.7f, 604.6f, 481.6f, 344.3f, 562.2f, 0f);
      p.lineTo(0f, 0f);
      p.close();

      p = patternPaths[6] = new Path();
      p.moveTo(146f, 0f);
      p.lineTo(0f, 0f);
      p.lineTo(0f, 768f);
      p.lineTo(394.2f, 768f);
      p.cubicTo(327.7f, 475.3f, 228.5f, 201f, 146f, 0f);
      p.close();
    }

    for (int i = 0; i < NUM_PATHS; i++) {
      // Color is 0xAARRGGBB, so alpha << 24 will create a color with (alpha)% black.
      // Although the color components don't really matter, since the backing bitmap cache is
      // ALPHA_8.
      tempPaint.setColor(patternLightness[i] << 24);
      canvas.drawPath(patternPaths[i], tempPaint);
    }

    canvas.restore();
    tempPaint.reset();
  }

  @VisibleForTesting
  public void scaleCanvasToBounds(Canvas canvas, Bitmap bitmap, Rect drawableBounds) {
    int bitmapWidth = bitmap.getWidth();
    int bitmapHeight = bitmap.getHeight();
    float scaleX = drawableBounds.width() / (float) bitmapWidth;
    float scaleY = drawableBounds.height() / (float) bitmapHeight;

    // First scale both sides to fit independently.
    canvas.scale(scaleX, scaleY);
    if (scaleY > scaleX) {
      // Adjust x-scale to maintain aspect ratio using the pivot, so that more of the texture
      // and less of the blank space on the left edge is seen.
      canvas.scale(scaleY / scaleX, 1f, SCALE_FOCUS_X * bitmapWidth, 0f);
    } else if (scaleX > scaleY) {
      // Adjust y-scale to maintain aspect ratio using the pivot, so that an intersection of
      // two "circles" can always be seen.
      canvas.scale(1f, scaleX / scaleY, 0f, SCALE_FOCUS_Y * bitmapHeight);
    }
  }

  @Override
  public void setAlpha(int i) {
    // Ignore
  }

  @Override
  public void setColorFilter(ColorFilter colorFilter) {
    // Ignore
  }

  @Override
  public int getOpacity() {
    return PixelFormat.UNKNOWN;
  }

  /**
   * Sets the color used as the base color of this pattern drawable. The alpha component of the
   * color will be ignored.
   */
  public void setColor(int color) {
    final int r = Color.red(color);
    final int g = Color.green(color);
    final int b = Color.blue(color);
    this.color = Color.argb(COLOR_ALPHA_INT, r, g, b);
    invalidateSelf();
  }

  /**
   * @return The color used as the base color of this pattern drawable. The alpha component of this
   *     is always 255.
   */
  public int getColor() {
    return Color.argb(255, Color.red(color), Color.green(color), Color.blue(color));
  }
}