ImageSpec.java

/**
 * Copyright (c) 2017-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */

package com.facebook.litho.widget;

import android.content.res.TypedArray;
import android.graphics.drawable.Drawable;
import android.widget.ImageView.ScaleType;

import com.facebook.litho.ComponentContext;
import com.facebook.litho.ComponentLayout;
import com.facebook.litho.Diff;
import com.facebook.litho.DrawableMatrix;
import com.facebook.litho.MatrixDrawable;
import com.facebook.litho.Output;
import com.facebook.litho.R;
import com.facebook.litho.Size;
import com.facebook.litho.SizeSpec;
import com.facebook.litho.annotations.FromBoundsDefined;
import com.facebook.litho.annotations.MountSpec;
import com.facebook.litho.annotations.OnBind;
import com.facebook.litho.annotations.OnBoundsDefined;
import com.facebook.litho.annotations.OnCreateMountContent;
import com.facebook.litho.annotations.OnLoadStyle;
import com.facebook.litho.annotations.OnMeasure;
import com.facebook.litho.annotations.OnMount;
import com.facebook.litho.annotations.OnUnmount;
import com.facebook.litho.annotations.Prop;
import com.facebook.litho.annotations.ResType;
import com.facebook.litho.annotations.ShouldUpdate;
import com.facebook.litho.utils.MeasureUtils;

import static com.facebook.litho.SizeSpec.UNSPECIFIED;

/**
 * A component that is able to display drawable resources. It takes a drawable
 * resource ID as prop.
 *
 * @prop drawable Drawable to display.
 * @prop scaleType Scale type for the drawable within the container.
 */
@MountSpec(isPureRender = true, poolSize = 30)
class ImageSpec {

  private static final ScaleType[] SCALE_TYPE = ScaleType.values();

  @OnLoadStyle
  static void onLoadStyle(
      ComponentContext c,
      Output<Drawable> drawable,
      Output<ScaleType> scaleType) {

    final TypedArray a = c.obtainStyledAttributes(R.styleable.Image, 0);

    for (int i = 0, size = a.getIndexCount(); i < size; i++) {
      final int attr = a.getIndex(i);

      if (attr == R.styleable.Image_android_src) {
        drawable.set(c.getResources().getDrawable(a.getResourceId(attr, 0)));
      } else if (attr == R.styleable.Image_android_scaleType) {
        scaleType.set(SCALE_TYPE[a.getInteger(attr, -1)]);
      }
    }

    a.recycle();
  }

  @OnMeasure
  static void onMeasure(
      ComponentContext c,
      ComponentLayout layout,
      int widthSpec,
      int heightSpec,
      Size size,
      @Prop(resType = ResType.DRAWABLE) Drawable drawable) {
    if (drawable == null ||
        drawable.getIntrinsicWidth() <= 0 ||
        drawable.getIntrinsicHeight() <= 0) {
      size.width = 0;
      size.height = 0;
      return;
    }

    final int intrinsicHeight = drawable.getIntrinsicHeight();
    final int intrinsicWidth = drawable.getIntrinsicWidth();

    if (SizeSpec.getMode(widthSpec) == UNSPECIFIED &&
        SizeSpec.getMode(heightSpec) == UNSPECIFIED) {
      size.width = intrinsicWidth;
      size.height = intrinsicHeight;
      return;
    }

    final float aspectRatio = intrinsicWidth / (float) intrinsicHeight;
    MeasureUtils.measureWithAspectRatio(
        widthSpec,
        heightSpec,
        intrinsicWidth,
        intrinsicHeight,
        aspectRatio,
        size);
  }

  @OnBoundsDefined
  static void onBoundsDefined(
      ComponentContext c,
      ComponentLayout layout,
      @Prop(resType = ResType.DRAWABLE) Drawable drawable,
      @Prop(optional = true) ScaleType scaleType,
      Output<DrawableMatrix> drawableMatrix,
      Output<Integer> drawableWidth,
      Output<Integer> drawableHeight) {

    final int horizontalPadding = layout.getPaddingLeft() + layout.getPaddingRight();
    final int verticalPadding = layout.getPaddingTop() + layout.getPaddingBottom();

    if (ScaleType.FIT_XY == scaleType
        || drawable == null
        || drawable.getIntrinsicWidth() <= 0
        || drawable.getIntrinsicHeight() <= 0) {
      drawableMatrix.set(null);
      drawableWidth.set(layout.getWidth() - horizontalPadding);
      drawableHeight.set(layout.getHeight() - verticalPadding);
    } else {
      final DrawableMatrix matrix = DrawableMatrix.create(
          drawable,
          scaleType,
          layout.getWidth() - horizontalPadding,
          layout.getHeight() - verticalPadding);

      drawableMatrix.set(matrix);
      drawableWidth.set(drawable.getIntrinsicWidth());
      drawableHeight.set(drawable.getIntrinsicHeight());
    }
  }

  @OnCreateMountContent
  static MatrixDrawable onCreateMountContent(ComponentContext c) {
    return new MatrixDrawable();
  }

  @OnMount
  static void onMount(
      ComponentContext c,
      MatrixDrawable matrixDrawable,
      @Prop(resType = ResType.DRAWABLE) Drawable drawable,
      @FromBoundsDefined DrawableMatrix drawableMatrix) {
    matrixDrawable.mount(drawable, drawableMatrix);
  }

  @OnBind
  static void onBind(
      ComponentContext c,
      MatrixDrawable mountedDrawable,
      @FromBoundsDefined Integer drawableWidth,
      @FromBoundsDefined Integer drawableHeight) {
    mountedDrawable.bind(drawableWidth, drawableHeight);
  }

  @OnUnmount
  static void onUnmount(
      ComponentContext c,
      MatrixDrawable convertDrawable,
      @Prop(resType = ResType.DRAWABLE) Drawable drawable) {
    convertDrawable.unmount();
  }

  @ShouldUpdate(onMount = true)
  static boolean shouldUpdate(
      Diff<ScaleType> scaleType,
      Diff<Drawable> drawable) {
    return (scaleType.getNext() != scaleType.getPrevious()) ||
        drawable.getNext() != drawable.getPrevious();
  }
}