深度剖析之 Material Design Android Library_com.github.navasmdc:materialdesign-优快云博客

本文链接：https://blog.youkuaiyun.com/AnalyzeSystem/article/details/50249037

本文详细剖析了MaterialDesignAndroidLibrary开源项目的实现细节，包括按钮、开关、进度条等组件的源码分析，以及如何正确导入和解决冲突问题。通过实例演示，帮助开发者深入理解Android组件的自定义实现和事件处理逻辑。

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剖析项目名称： Material Design Android Library
剖析原项目地址：https://github.com/navasmdc/MaterialDesignLibrary
剖析理由：只知其然而不知其所以然，如此不好。想要快速的进阶，不走寻常路，剖析开源项目，深入理解扩展知识，仅仅这样还不够，还需要如此：左手爱哥的设计模式，右手重构改善既有设计，如此漫长打坐，回过头再看来时的路，书已成山，相信翔哥说的，量变引起质变。，

How to use
Components
- Buttons
  - Flat Button
  - Rectangle Button
  - Float Button
  - Float small button
- switches
  - CheckBox
  - Switch
- progress
  - Progress bar circular circular indeterminate
  - Progress bar indeterminate
  - Progress bar indeterminate determinater
  - Progress bar determinate
  - Slider
  - Slider with number indicator
widgets
- SnackBar
- Dialog
- Color Selector

如果你想要使用这个库,您只需要下载MaterialDesign项目,将其导入到您的工作区,并添加这个项目作为一个依赖，导入方法（Android Studio 编辑器）：

repositories {
    jcenter()
}

dependencies {
    compile 'com.github.navasmdc:MaterialDesign:1.5@aar'
}

比较早的Android Studio版本导入该库是没问题的，但是随着时间的变化，Gradle自动comple了 ‘com.android.support:design:22.2.1’该库，该库和我们将要导入的库有自定义属性rippleColor属性重复定义冲突，摆在我们面前的有两个办法，一试把Material Design Android Library下载下来，修改该属性名字和关联类，另一种就是更换库(该库兼容到16):

repositories {
    maven { url "https://jitpack.io" }
}

compile 'com.github.vajro:MaterialDesignLibrary:1.6'

该库自定义控件包含自定义属性，如果你在xml里面需要使用到它们，需要导入下面这句话（materialdesign根据自己喜好修改，这句话是属于自定义属性相关知识的内容，如果不了解请参考官方资料）：

  xmlns:materialdesign="http://schemas.android.com/apk/res-auto"

如果你要使用滚动视图,建议您使用这个库中提供的ScrollView来避免自定义组件的问题。使用这个组件方法:

<com.gc.materialdesign.views.ScrollView 
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:materialdesign="http://schemas.android.com/apk/res-auto"
   android:id="@+id/scroll"
   android:layout_width="match_parent"
   android:layout_height="match_parent">
</com.gc.materialdesign.views.ScrollView>

先来一睹为快吧，看一下运行效果图(模拟器录制有点卡，换了游视秀app录制的.mp4,再通过桌面录屏工具录制播放的.mp4成gif，如果你感兴趣可以试试)：

Button控件提供了ButtonFlat、ButtonRectangle、ButtonFloat、ButtonFloatSmall四个控件，下面我们逐步分析它。这几个类都继承自定义的抽象类Button，而Button继承自CustomView.

那么先来看CustomView类

public class CustomView extends RelativeLayout {

    /**不能点击的背景色*/ 
    final int disabledBackgroundColor = Color.parseColor("#E2E2E2");

    /**能点击的背景色*/ 
    int beforeBackground;

    /**自定义ScrollView用于判断是否拦截Touch事件*/ 
    public boolean isLastTouch = false;

    /**是否在执行动画，根据这个参数选择重绘*/
    boolean animation = false;

   public CustomView(Context context, AttributeSet attrs) {
        super(context, attrs);
   }

   /**
    * 设置是否可点击，调用View的setEnable设置，与此同时，根据enabled参数，选择设置背景颜色
    **/ 
   public void setEnabled(boolean enabled) {
        super.setEnabled(enabled);
        if(enabled) {
            this.setBackgroundColor(this.beforeBackground);
        } else {
            this.setBackgroundColor(this.disabledBackgroundColor);
        }
        //调用重绘  
        this.invalidate();
    }

   /**
    * 重写RelativeLayout继承自ViewGroup的动画启动方法，并对animation重写赋值为true
    **/ 
    protected void onAnimationStart() {
        super.onAnimationStart();
        this.animation = true;
    }

   /**
    * 重写RelativeLayout继承自ViewGroup的动画结束方法，并对animation重写赋值为false
    **/ 
    protected void onAnimationEnd() {
        super.onAnimationEnd();
        this.animation = false;
    }

    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if(this.animation) {
            //如果动画是启动状态，就调用重绘自身
            this.invalidate();
        }
    }
}

抽象Button类

public abstract class Button extends CustomView {

  static final String ANDROIDXML = "http://schemas.android.com/apk/res/android";
    /**最小宽度*/
    int minWidth;
    /**最小高度*/
    int minHeight;
    /**背景*/
    int background;
    /**波纹绘制速度*/
    float rippleSpeed = 12.0F;
    /**波纹大小*/
    int rippleSize = 3;
    /**波纹颜色*/
    Integer rippleColor;
    /**点击事件*/
    OnClickListener onClickListener;
    /**是否有点击之后的波纹*/
    boolean clickAfterRipple = true;
    /**背景颜色*/
    int backgroundColor = Color.parseColor("#1E88E5");
    /**文字控件TextView*/
    TextView textButton;
    /**X坐标*/
    float x = -1.0F;
    /**Y坐标*/
    float y = -1.0F;
    /**绘制的范围*/
    float radius = -1.0F;

    public Button(Context context, AttributeSet attrs) {
        super(context, attrs);
        //设置默认值
        this.setDefaultProperties();
        //获取属性，点击后是否有波纹效果，默认有
        this.clickAfterRipple = attrs.getAttributeBooleanValue("http://schemas.android.com/apk/res-auto", "animate", true);
        //空实现方法，供子类使用
        this.setAttributes(attrs);
        this.beforeBackground = this.backgroundColor;
        if(this.rippleColor == null) {
            //波纹颜色
            this.rippleColor = Integer.valueOf(this.makePressColor());
        }

    }
}

makePressColor（）方法获取的是波纹颜色：

 protected int makePressColor() {
        //backgroundColor 颜色值通过位移与225（0-225代表的是颜色值的深度，数值越大，颜色越深，RGB是红绿蓝三色对应的数值组合，
        //这里通过位移获取到RGB各自对应的色值），再把RGB对应的数值降低30，最后通过Color提供的RGB方法重新生成颜色即rippleColor.
        int r = this.backgroundColor >> 16 & 255;
        int g = this.backgroundColor >> 8 & 255;
        int b = this.backgroundColor >> 0 & 255;
        r = r - 30 < 0?0:r - 30;
        g = g - 30 < 0?0:g - 30;
        b = b - 30 < 0?0:b - 30;
        return Color.rgb(r, g, b);
    }

CustomView 继承自RelativeLayout，所以拥有事件分发拦截方法onInterceptTouchEvent，这里通过拦截事件，交给 onTouchEvent(MotionEvent event)处理。

  public boolean onInterceptTouchEvent(MotionEvent ev) {
        return true;
  }

   public boolean onTouchEvent(MotionEvent event) {
        this.invalidate();
        if(this.isEnabled()) {
            //允许点击，isLastTouch赋值为true，自定义ScrollView了通过该参数控制是否出Touch事件
            this.isLastTouch = true;
            if(event.getAction() == 0) {

    //action参照如下定义
    /**
     * Constant for {@link #getActionMasked}: A pressed gesture has started, the
     * motion contains the initial starting location.
     * <p>
     * This is also a good time to check the button state to distinguish
     * secondary and tertiary button clicks and handle them appropriately.
     * Use {@link #getButtonState} to retrieve the button state.
     * </p>
     */
   // public static final int ACTION_DOWN             = 0;

    /**
     * Constant for {@link #getActionMasked}: A pressed gesture has finished, the
     * motion contains the final release location as well as any intermediate
     * points since the last down or move event.
     */
   // public static final int ACTION_UP               = 1;

    /**
     * Constant for {@link #getActionMasked}: A change has happened during a
     * press gesture (between {@link #ACTION_DOWN} and {@link #ACTION_UP}).
     * The motion contains the most recent point, as well as any intermediate
     * points since the last down or move event.
     */
   // public static final int ACTION_MOVE             = 2;
    /**
     * Constant for {@link #getActionMasked}: The current gesture has been aborted.
     * You will not receive any more points in it.  You should treat this as
     * an up event, but not perform any action that you normally would.
     */
    //public static final int ACTION_CANCEL           = 3;

                 //按下时计算波纹的size，并记录坐标
                this.radius = (float)(this.getHeight() / this.rippleSize);
                this.x = event.getX();
                this.y = event.getY();
            } else if(event.getAction() == 2) {
                //移动时计算波纹的size，并记录坐标
                this.radius = (float)(this.getHeight() / this.rippleSize);
                this.x = event.getX();
                this.y = event.getY();
                //判断移动中的坐标还是否在当前视图范围内
                if(event.getX() > (float)this.getWidth() || event.getX() < 0.0F || event.getY() > (float)this.getHeight() || event.getY() < 0.0F) {
                    this.isLastTouch = false;
                    this.x = -1.0F;
                    this.y = -1.0F;
                }
            } 
            //手抬起时，计算相关变量值，并判断是否回调onclick函数
            else if(event.getAction() == 1) {
                if(event.getX() <= (float)this.getWidth() && event.getX() >= 0.0F && event.getY() <= (float)this.getHeight() && event.getY() >= 0.0F) {
                    ++this.radius;
                    if(!this.clickAfterRipple && this.onClickListener != null) {
                        this.onClickListener.onClick(this);
                    }
                } else {
                    this.isLastTouch = false;
                    this.x = -1.0F;
                    this.y = -1.0F;
                }
            } else if(event.getAction() == 3) {
                //取消绘制
                this.isLastTouch = false;
                this.x = -1.0F;
                this.y = -1.0F;
            }
        }

        return true;
    }

内部提供一个绘图方法，创一个大小的圆形图，并绘制到画布，返回创建的Bitmap，并绑定监听

 public Bitmap makeCircle() {
        Bitmap output = Bitmap.createBitmap(this.getWidth() - Utils.dpToPx(6.0F, this.getResources()), this.getHeight() - Utils.dpToPx(7.0F, this.getResources()), Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        canvas.drawARGB(0, 0, 0, 0);
        Paint paint = new Paint();
        paint.setAntiAlias(true);
        paint.setColor(this.rippleColor.intValue());
        canvas.drawCircle(this.x, this.y, this.radius, paint);
        if(this.radius > (float)(this.getHeight() / this.rippleSize)) {
            this.radius += this.rippleSpeed;
        }

        if(this.radius >= (float)this.getWidth()) {
            this.x = -1.0F;
            this.y = -1.0F;
            this.radius = (float)(this.getHeight() / this.rippleSize);
            if(this.onClickListener != null && this.clickAfterRipple) {
                this.onClickListener.onClick(this);
            }
        }

        return output;
    }

现在开始正真分析这几个控件了，ButtonFlat：

public class ButtonFlat extends Button {

    protected void setAttributes(AttributeSet attrs) {
        String text = null;
        //获取android定义的属性android:text=""
        int textResource = attrs.getAttributeResourceValue("http://schemas.android.com/apk/res/android", "text", -1);
        if(textResource != -1) {
            text = this.getResources().getString(textResource);
        } else {
            text = attrs.getAttributeValue("http://schemas.android.com/apk/res/android", "text");
        }

        if(text != null) {
            //如果有text值，则创建一个TextView，并赋值
            this.textButton = new TextView(this.getContext());
            this.textButton.setText(text.toUpperCase());
            this.textButton.setTextColor(this.backgroundColor);
            this.textButton.setTypeface((Typeface)null, 1);
            LayoutParams bacgroundColor = new LayoutParams(-2, -2);
            bacgroundColor.addRule(13, -1);
            this.textButton.setLayoutParams(bacgroundColor);
            //把这个textView添加到Layout里面作为子View
            this.addView(this.textButton);
        }

        //获取背景属性
        int bacgroundColor1 = attrs.getAttributeResourceValue("http://schemas.android.com/apk/res/android", "background", -1);
        if(bacgroundColor1 != -1) {
            this.setBackgroundColor(this.getResources().getColor(bacgroundColor1));
        } else {
            this.background = attrs.getAttributeIntValue("http://schemas.android.com/apk/res/android", "background", -1);
            if(this.background != -1) {
                this.setBackgroundColor(this.background);
            }
        }

    }
}

   protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if(this.x != -1.0F) {
            Paint paint = new Paint();
            paint.setAntiAlias(true);
            paint.setColor(this.makePressColor());
            //根据按下坐标画圆
            canvas.drawCircle(this.x, this.y, this.radius, paint);
            if(this.radius > (float)(this.getHeight() / this.rippleSize)) {
                this.radius += this.rippleSpeed;
            }

            if(this.radius >= (float)this.getWidth()) {
                //当波纹的大小超出了视图范围，就不在绘制并通过OnClickListener回调到主线程处理相关事件
                this.x = -1.0F;
                this.y = -1.0F;
                this.radius = (float)(this.getHeight() / this.rippleSize);
                if(this.onClickListener != null && this.clickAfterRipple) {
                    this.onClickListener.onClick(this);
                }
            }
            //再调重绘绘制自身（绘制范围还没超出限定范围还会继续继续绘制根据radius大小的改变）
            this.invalidate();
        }

      }

ButtonFlot相比较ButtonFlat而言，把内部创建的TextView替换成了ImageView,改变不大，在绘制时onDraw方法里面drawBitmap(…)调用了cropCircle和makeCircle方法得到波纹bitmap:

 public Bitmap cropCircle(Bitmap bitmap) {

        //..............此处略...............

        canvas.drawCircle((float)(bitmap.getWidth() / 2), (float)(bitmap.getHeight() / 2), (float)(bitmap.getWidth() / 2), paint);
        //不同的模式呈现结果是不同的，这里用的SRC_IN:取两层绘制交集。显示上层。
        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));
        canvas.drawBitmap(bitmap, rect, rect, paint);
        return output;
    }

其他几个Button的自定义暂时就不提了，基本实现都差不多，上面效果图里面有个底部Button弹出效果，在xml布局如下（通过自定义属性传入动画状态和图标资源）：

 <com.gc.materialdesign.views.ButtonFloat
                android:id="@+id/buttonFloat"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_alignParentRight="true"
                android:layout_alignParentBottom="true"
                android:layout_marginRight="24dp"
                android:background="#1E88E5"
                materialdesign:animate="true"
                materialdesign:iconDrawable="@drawable/ic_action_new" />

在ButtonFloat里面通过实现父类的空方法里，获取了这两个属性，同时执行相应的动画：

  protected void setAttributes(AttributeSet attrs) {
        //..........略..........
        iconResource = attrs.getAttributeResourceValue("http://schemas.android.com/apk/res-auto", "iconDrawable", -1);
        if(iconResource != -1) {
            this.drawableIcon = this.getResources().getDrawable(iconResource);
        }

        final boolean animate = attrs.getAttributeBooleanValue("http://schemas.android.com/apk/res-auto", "animate", false);
        this.post(new Runnable() {
            public void run() {
                ButtonFloat.this.showPosition = ViewHelper.getY(ButtonFloat.this) - (float)Utils.dpToPx(24.0F, ButtonFloat.this.getResources());
                ButtonFloat.this.hidePosition = ViewHelper.getY(ButtonFloat.this) + (float)(ButtonFloat.this.getHeight() * 3);
                if(animate) {
                    ViewHelper.setY(ButtonFloat.this, ButtonFloat.this.hidePosition);
                    ButtonFloat.this.show();
                }

            }
        });
    }

动画显示和隐藏的控制方法（原理：通过插值器和Y值变化控制）：

  public void show() {
        ObjectAnimator animator = ObjectAnimator.ofFloat(this, "y", new float[]{this.showPosition});
        animator.setInterpolator(new BounceInterpolator());
        animator.setDuration(1500L);
        animator.start();
        this.isShow = true;
    }

    public void hide() {
        ObjectAnimator animator = ObjectAnimator.ofFloat(this, "y", new float[]{this.hidePosition});
        animator.setInterpolator(new BounceInterpolator());
        animator.setDuration(1500L);
        animator.start();
        this.isShow = false;
    }

Button自定义暂时告一段落，接着来看Switchs相关控件的自定义。

  <com.gc.materialdesign.views.CheckBox
                android:id="@+id/checkBox"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:layout_centerInParent="true"
                android:background="#1E88E5"
                materialdesign:check="true" />

checkBox按下效果有个圆形出现，而颜色值是根据isChecked改变的，实现方法在onTouch的down up 通过调用重绘，onDraw里绘制出图像

  public void invalidate() {
        //重绘根据选中状态，改变选中图片
        this.checkView.invalidate();
        super.invalidate();
    }
  protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if(this.press) {
            Paint paint = new Paint();
            paint.setAntiAlias(true);
            paint.setColor(this.check?this.makePressColor():Color.parseColor("#446D6D6D"));
            canvas.drawCircle((float)(this.getWidth() / 2), (float)(this.getHeight() / 2), (float)(this.getWidth() / 2), paint);
            this.invalidate();
        }

    }

checkView是CheckBox类里的内部类Check，继承自View类：

 class Check extends View {
 public void changeBackground() {
            if(CheckBox.this.check) {//根据不同的状态选择不同的图片
                this.setBackgroundResource(drawable.background_checkbox_check);
                LayerDrawable layer = (LayerDrawable)this.getBackground();
                GradientDrawable shape = (GradientDrawable)layer.findDrawableByLayerId(id.shape_bacground);
                shape.setColor(CheckBox.this.backgroundColor);
            } else {
                this.setBackgroundResource(drawable.background_checkbox_uncheck);
            }

        }

        protected void onDraw(Canvas canvas) {
            super.onDraw(canvas);

            //...............此处略................... 

            Rect src = new Rect(40 * CheckBox.this.step, 0, 40 * CheckBox.this.step + 40, 40);
            Rect dst = new Rect(0, 0, this.getWidth() - 2, this.getHeight());
            canvas.drawBitmap(this.sprite, src, dst, (Paint)null);
        }
    }
 }

com.gc.materialdesign.views.Switch控件就不贴代码了简单说一下原理，onTouch时判断滑动的距离是否大于某个固定值，从而改变状态，调用回调函数，在onDraw里面重绘改变界面。这里还借助了第三方开源动画库，调用 ViewHelper.setX(）方法。关于进度自定义控件ProgressBarCircularIndeterminate实现原理：先绘制一个圆动态改变半径，然后在绘制一个圆通个xfermode最后得到一个周长弧，累赘代码就不贴了，通个onDraw方法我学到了一点知识：绘制内容抽离到方法，通个句柄选择绘制，再通过调用自身再次绘制未执行部分

  protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if(!this.firstAnimationOver) {
            this.drawFirstAnimation(canvas);
        }

        if(this.cont > 0) {
            this.drawSecondAnimation(canvas);
        }

        this.invalidate();
    }

Slider类的自定义的实现原理，在setAttributes根据showNumberIndicator为true时，选择创建弹出浮动在上方的圆和值的dialog，onTouch是判断选择修改dialog的隐藏、显示、位置和值。代码就不贴了。SnackBar继承自Dialog，没啥好说的，就onCreate的view布局，引入基本配置，onDismis 、show方法执行动画，此处略过了。ColorSelector也是一个Dialog没啥好说的，三个Slider控件的值组合成Color从而改变颜色，通个监听及时回调，这里也略过了。

之前提到的滚动视图建议用该库自定义的ScrollView（判断了子类是否是CustomView，根据isLastTouch属性判断是否拦截Touch事件）：


public class ScrollView extends android.widget.ScrollView {
    public ScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public boolean onTouchEvent(MotionEvent ev) {
        for(int i = 0; i < ((ViewGroup)this.getChildAt(0)).getChildCount(); ++i) {
            try {
                CustomView e = (CustomView)((ViewGroup)this.getChildAt(0)).getChildAt(i);
                if(e.isLastTouch) {
                    e.onTouchEvent(ev);
                    return true;
                }
            } catch (ClassCastException var4) {
                ;
            }
        }

        return super.onTouchEvent(ev);
    }
}