material-components_material-components-android/lib/java/android/support/design/button/MaterialButtonHelper.java

/*
 * Copyright (C) 2017 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 android.support.design.button;

import static android.support.annotation.RestrictTo.Scope.LIBRARY_GROUP;

import android.annotation.TargetApi;
import android.content.res.ColorStateList;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.GradientDrawable;
import android.graphics.drawable.InsetDrawable;
import android.graphics.drawable.RippleDrawable;
import android.graphics.drawable.StateListDrawable;
import android.os.Build.VERSION;
import android.os.Build.VERSION_CODES;
import android.support.annotation.Nullable;
import android.support.annotation.RestrictTo;
import android.support.design.resources.MaterialResources;
import android.support.design.ripple.RippleUtils;
import android.support.v4.graphics.ColorUtils;
import android.support.v4.view.ViewCompat;

/** @hide */
@RestrictTo(LIBRARY_GROUP)
class MaterialButtonHelper {

  private static final int[] STATE_PRESSED =
      new int[] {android.R.attr.state_enabled, android.R.attr.state_pressed};
  private static final int[] STATE_ENABLED = new int[] {android.R.attr.state_enabled};
  private static final int[] STATE_EMPTY = new int[] {};

  private final MaterialButton materialButton;

  private int insetLeft;
  private int insetRight;
  private int insetTop;
  private int insetBottom;
  private float cornerRadius;
  @Nullable private ColorStateList backgroundTint;
  @Nullable private ColorStateList strokeColor;
  @Nullable private ColorStateList rippleColor;
  private int strokeWidth;

  public MaterialButtonHelper(MaterialButton button) {
    materialButton = button;
  }

  public void loadFromAttributes(TypedArray attributes) {
    insetLeft = attributes.getDimensionPixelOffset(R.styleable.MaterialButton_android_insetLeft, 0);
    insetRight =
        attributes.getDimensionPixelOffset(R.styleable.MaterialButton_android_insetRight, 0);
    insetTop = attributes.getDimensionPixelOffset(R.styleable.MaterialButton_android_insetTop, 0);
    insetBottom =
        attributes.getDimensionPixelOffset(R.styleable.MaterialButton_android_insetBottom, 0);
    cornerRadius = attributes.getDimensionPixelSize(R.styleable.MaterialButton_cornerRadius, 0);
    backgroundTint =
        MaterialResources.getColorStateList(
            materialButton.getContext(),
            attributes,
            R.styleable.MaterialButton_buttonBackgroundTint);
    strokeColor =
        MaterialResources.getColorStateList(
            materialButton.getContext(), attributes, R.styleable.MaterialButton_strokeColor);
    rippleColor =
        MaterialResources.getColorStateList(
            materialButton.getContext(), attributes, R.styleable.MaterialButton_rippleColor);
    strokeWidth = attributes.getDimensionPixelSize(R.styleable.MaterialButton_strokeWidth, 0);
    ViewCompat.setBackground(
        materialButton,
        VERSION.SDK_INT >= VERSION_CODES.LOLLIPOP
            ? createBackgroundLollipop()
            : createBackgroundCompat());
  }

  /**
   * Create StateListDrawable background for KitKat (API 19) and earlier API versions
   *
   * @return Drawable representing background for this button.
   */
  private Drawable createBackgroundCompat() {
    int pressedBackgroundColor =
        ColorUtils.compositeColors(
            rippleColor != null ? rippleColor.getColorForState(STATE_PRESSED, 0) : 0,
            backgroundTint != null ? backgroundTint.getColorForState(STATE_PRESSED, 0) : 0);
    int enabledBackgroundColor = backgroundTint.getColorForState(STATE_ENABLED, 0);
    int disabledBackgroundColor = backgroundTint.getColorForState(STATE_EMPTY, 0);

    Drawable pressedBackground =
        createBackgroundCompatForState(STATE_PRESSED, pressedBackgroundColor);
    Drawable enabledBackground =
        createBackgroundCompatForState(STATE_ENABLED, enabledBackgroundColor);
    Drawable disabledBackground =
        createBackgroundCompatForState(STATE_EMPTY, disabledBackgroundColor);

    StateListDrawable stateListDrawable = new StateListDrawable();
    stateListDrawable.addState(STATE_PRESSED, pressedBackground);
    stateListDrawable.addState(STATE_ENABLED, enabledBackground);
    stateListDrawable.addState(STATE_EMPTY, disabledBackground);

    return stateListDrawable;
  }

  private InsetDrawable createBackgroundCompatForState(int[] state, int backgroundColor) {
    GradientDrawable bgDrawable = new GradientDrawable();
    bgDrawable.setCornerRadius(cornerRadius);
    bgDrawable.setColor(backgroundColor);
    if (strokeColor != null) {
      bgDrawable.setStroke(strokeWidth, strokeColor.getColorForState(state, 0));
    }
    return new InsetDrawable(bgDrawable, insetLeft, insetTop, insetRight, insetBottom);
  }

  /**
   * Create RippleDrawable background for Lollipop (API 21) and later API versions
   *
   * @return Drawable representing background for this button.
   */
  @TargetApi(VERSION_CODES.LOLLIPOP)
  private Drawable createBackgroundLollipop() {
    GradientDrawable bgDrawable = new GradientDrawable();
    bgDrawable.setCornerRadius(cornerRadius);
    bgDrawable.setColor(backgroundTint);
    if (strokeColor != null) {
      bgDrawable.setStroke(strokeWidth, strokeColor);
    }
    InsetDrawable bgInsetDrawable =
        new InsetDrawable(bgDrawable, insetLeft, insetTop, insetRight, insetBottom);

    GradientDrawable maskDrawable = new GradientDrawable();
    maskDrawable.setCornerRadius(cornerRadius);
    maskDrawable.setColor(Color.WHITE);
    InsetDrawable maskInsetDrawable = new InsetDrawable(maskDrawable, 0);

    return new RippleDrawable(
        RippleUtils.convertToRippleDrawableColor(rippleColor), bgInsetDrawable, maskInsetDrawable);
  }
}