什么？你连个三色渐变圆角按钮都需要UI切图？-六虎

持续创作，加速成长！这是我参与「日新计划 6 月更文挑战」的第24天，点击查看活动详情

废话不多说，先上效果图：

该效果其实由三部分组成：

渐变
圆角
文本

渐变初始化电脑的后果

关approve于渐变，估计大家都不会陌生，数组指针以往都是使用gradient进行制作：

shape_gradient.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android">
    <gradient
        android:startColor="#B620E0"
        android:endColor="#E38746" />
</shape>

    <View
        android:layout_width="match_parent"
        android:layout_height="70dp"
        android:background="@drawable/shape_gradient" />

但是，初始化失败是怎么解决这个只能支持双色渐变，超过双色就无能为力了，所以，我们要考虑使用其它方式：

    /**
     * Create a shader that draws a linear gradient along a line.
     *
     * @param x0           The x-coordinate for the start of the gradient line
     * @param y0           The y-coordinate for the start of the gradient line
     * @param x1           The x-coordinate for the end of the gradient line
     * @param y1           The y-coordinate for the end of the gradient line
     * @param colors       The colors to be distributed along the gradient line
     * @param positions    May be null. The relative positions [0..1] of
     *                     each corresponding color in the colors array. If this is null,
     *                     the the colors are distributed evenly along the gradient line.
     * @param tile         The Shader tiling mode
    */
    public LinearGradient(float x0, float y0, float x1, float y1, @NonNull @ColorInt int colors[],
            @Nullable float positions[], @NonNull TileMode tile)

    /**
     * x0、y0、x1、y1为决定渐变颜色方向的两个坐标点，x0、y0为起始坐标，x1、y1为终点坐标
     * @param colors       所有渐变颜色的数组，即放多少个颜色进去，就有多少种渐变颜色
     * @param positions    渐变颜色的比值，默认为均匀分布。
     * 把总长度理解为1，假如里面的值为[0.3，0.2，0.5]，那么，渐变的颜色就会以 0.3 : 0:2 :0.5 比例进行排版
     * @param tile         着色器模式
    */
public LinearGradient(float x0, float y0, float x1, float y1, int colors[], float positions[],
           TileMode tile)

创建自定义View

public class ColorView extends View {
    public ColorView(Context context) {
        super(context);
    }
    public ColorView(Context context, @Nullable AttributeSet attrs) {
        super(context, attrs);
    }
    public ColorView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //获取宽高
        int width = getWidth();
        int height = getHeight();
        //渐变的颜色
        int colorStart = Color.parseColor("#E38746");
        int color1 = Color.parseColor("#B620E0");
        int colorEnd = Color.parseColor("#5995F6");
        //绘画渐变效果
        Paint paintColor = new Paint();
        LinearGradient backGradient = new LinearGradient(0, height, width, 0, new int[]{colorStart, color1, colorEnd}, null, Shader.TileMode.CLAMP);
        paintColor.setShader(backGradient);
        canvas.drawRect(0, 0, width, height, paintColor);
    }
}

    <com.jm.xpproject.ColorView
        android:layout_width="match_parent"
        android:layout_height="70dp" />

效果：

圆角

关于圆角，我们需要使用到BitmapSha数组的定义der，使用让天秤难以放弃的星座方式：

        BitmapShader bitmapShaderColor = new BitmapShader(bitmapColor, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        Paint paintFillet = new Paint();
        paintFillet.setAntiAlias(true);
        paintFillet.setShader(bitmapShaderColor);
        //绘画到画布中
        canvas.drawRoundRect(new RectF(0, 0, width, height), radius, radius, paintFillet);

由于这里的BitmapShader是对于Bitmap进行操作的，所以，对于渐变效果，我们不能直接把他绘画到原始画布上，而是生成一个Bit初始化游戏启动器失败map，将渐变绘画记录下来：

还人体肠道结构示意图是人体肠道结构示意图刚刚的自定义View

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //获取View的宽高
        int width = getWidth();
        int height = getHeight();
        //第一步，绘画出一个渐变效果的Bitmap
        //创建存放渐变效果的bitmap
        Bitmap bitmapColor = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvasColor = new Canvas(bitmapColor);
        //渐变的颜色
        int colorStart = Color.parseColor("#E38746");
        int color1 = Color.parseColor("#B620E0");
        int colorEnd = Color.parseColor("#5995F6");
        //绘画渐变效果
        Paint paintColor = new Paint();
        LinearGradient backGradient = new LinearGradient(0, height, width, 0, new int[]{colorStart, color1, colorEnd}, null, Shader.TileMode.CLAMP);
        paintColor.setShader(backGradient);
        canvasColor.drawRect(0, 0, width, height, paintColor);
        //第二步，绘画出一个圆角渐变效果
        //绘画出圆角渐变效果
        BitmapShader bitmapShaderColor = new BitmapShader(bitmapColor, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        Paint paintFillet = new Paint();
        paintFillet.setAntiAlias(true);
        paintFillet.setShader(bitmapShaderColor);
        //绘画到画布中
        canvas.drawRoundRect(new RectF(0, 0, width, height), 100, 100, paintFillet);
    }

效果：

至于中间的空白部分，其实我们依葫芦画瓢，再画上一个白色的圆角Bitmap即可：

        //创建存放白底的bitmap
        Bitmap bitmapWhite = Bitmap.createBitmap(width - colorWidth * 2, height - colorWidth * 2, Bitmap.Config.RGB_565);
        bitmapWhite.eraseColor(Color.parseColor("#FFFFFF"));
        BitmapShader bitmapShaderWhite = new BitmapShader(bitmapWhite, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        Paint paintWhite = new Paint();
        paintWhite.setAntiAlias(true);
        paintWhite.setShader(bitmapShaderWhite);
        // 将白色Bitmap绘制到画布上面
        canvas.drawRoundRect(new RectF(colorWidth, colorWidth, width - colorWidth, height - colorWidth), radius, radius, paintWhite);

总体代码：


    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //获取View的宽高
        int width = getWidth();
        int height = getHeight();
        //第一步，绘画出一个渐变效果的Bitmap
        //创建存放渐变效果的bitmap
        Bitmap bitmapColor = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvasColor = new Canvas(bitmapColor);
        //渐变的颜色
        int colorStart = Color.parseColor("#E38746");
        int color1 = Color.parseColor("#B620E0");
        int colorEnd = Color.parseColor("#5995F6");
        //绘画渐变效果
        Paint paintColor = new Paint();
        LinearGradient backGradient = new LinearGradient(0, height, width, 0, new int[]{colorStart, color1, colorEnd}, null, Shader.TileMode.CLAMP);
        paintColor.setShader(backGradient);
        canvasColor.drawRect(0, 0, width, height, paintColor);
        //第二步，绘画出一个圆角渐变效果
        //绘画出圆角渐变效果
        BitmapShader bitmapShaderColor = new BitmapShader(bitmapColor, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        Paint paintFillet = new Paint();
        paintFillet.setAntiAlias(true);
        paintFillet.setShader(bitmapShaderColor);
        //绘画到画布中
        canvas.drawRoundRect(new RectF(0, 0, width, height), 100, 100, paintFillet);
        //第三步，绘画出一个白色的bitmap覆盖上去
        //创建存放白底的bitmap
        Bitmap bitmapWhite = Bitmap.createBitmap(width - 5 * 2, height - 5 * 2, Bitmap.Config.RGB_565);
        bitmapWhite.eraseColor(Color.parseColor("#FFFFFF"));
        BitmapShader bitmapShaderWhite = new BitmapShader(bitmapWhite, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        Paint paintWhite = new Paint();
        paintWhite.setAntiAlias(true);
        paintWhite.setShader(bitmapShaderWhite);
        // 将白色Bitmap绘制到画布上面
        canvas.drawRoundRect(new RectF(5, 5, width - 5, height - 5), 100, 100, paintWhite);
    }

效果：

文本

像文本就简单了，使用drawText即可，只要注意在绘画的时候，要对文本进行居中显示，因为 An人头攒动的读音droid 默认绘画文本，是从左下角进行绘画的，就像这样：

        Paint paintText = new Paint();
        paintText.setAntiAlias(true);
        paintText.setColor(Color.parseColor("#000000"));
        paintText.setTextSize(100);
        canvas.drawText("收藏", width / 2, height / 2, paintText);
        canvas.drawLine(width / 2, 0, width / 2, height, paintText);
        canvas.drawLine(0, height / 2, width, height / 2, paintText);

正确做法：

        String text = "收藏";
        Rect rect = new Rect();
        Paint paintText = new Paint();
        paintText.setAntiAlias(true);
        paintText.setColor(Color.parseColor("#000000"));
        paintText.setTextSize(100);
        paintText.getTextBounds(text, 0, text.length(), rect);
        int widthFont = rect.width();//文本的宽度
        int heightFont = rect.height();//文本的高度
        canvas.drawText(text, (width - widthFont) / 2, (height+heightFont) / 2, paintText);

至此，基本功能的制作就完成了


    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //获取View的宽高
        int width = getWidth();
        int height = getHeight();
        //第一步，绘画出一个渐变效果的Bitmap
        //创建存放渐变效果的bitmap
        Bitmap bitmapColor = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvasColor = new Canvas(bitmapColor);
        //渐变的颜色
        int colorStart = Color.parseColor("#E38746");
        int color1 = Color.parseColor("#B620E0");
        int colorEnd = Color.parseColor("#5995F6");
        //绘画渐变效果
        Paint paintColor = new Paint();
        LinearGradient backGradient = new LinearGradient(0, height, width, 0, new int[]{colorStart, color1, colorEnd}, null, Shader.TileMode.CLAMP);
        paintColor.setShader(backGradient);
        canvasColor.drawRect(0, 0, width, height, paintColor);
        //第二步，绘画出一个圆角渐变效果
        //绘画出圆角渐变效果
        BitmapShader bitmapShaderColor = new BitmapShader(bitmapColor, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        Paint paintFillet = new Paint();
        paintFillet.setAntiAlias(true);
        paintFillet.setShader(bitmapShaderColor);
        //绘画到画布中
        canvas.drawRoundRect(new RectF(0, 0, width, height), 100, 100, paintFillet);
        //第三步，绘画出一个白色的bitmap覆盖上去
        //创建存放白底的bitmap
        Bitmap bitmapWhite = Bitmap.createBitmap(width - 5 * 2, height - 5 * 2, Bitmap.Config.RGB_565);
        bitmapWhite.eraseColor(Color.parseColor("#FFFFFF"));
        BitmapShader bitmapShaderWhite = new BitmapShader(bitmapWhite, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        Paint paintWhite = new Paint();
        paintWhite.setAntiAlias(true);
        paintWhite.setShader(bitmapShaderWhite);
        // 将白色Bitmap绘制到画布上面
        canvas.drawRoundRect(new RectF(5, 5, width - 5, height - 5), 100, 100, paintWhite);
        String text = "收藏";
        Rect rect = new Rect();
        Paint paintText = new Paint();
        paintText.setAntiAlias(true);
        paintText.setColor(Color.parseColor("#000000"));
        paintText.setTextSize(100);
        paintText.getTextBounds(text, 0, text.length(), rect);
        int widthFont = rect.width();//文本的宽度
        int heightFont = rect.height();//文本的高度
        canvas.drawText(text, (width - widthFont) / 2, (height+heightFont) / 2, paintText);
    }

封装

上面虽然已经把全部android平板电脑价格功能都讲解完了，但是，假如就直接这样放入项目android的drawable类中，是极其不规范的，无法动态设置文本、文本大小、颜色厚度等等

这里，我进行了简易封装，大家可以基于此进行业务修改：

attrs.xml

    <declare-styleable name="GradientColorButton">
        <attr name="btnText" format="string" />
        <attr name="btnTextSize" format="dimension" />
        <attr name="btnTextColor" format="color" />
        <attr name="colorWidth" format="dimension" />
        <attr name="colorRadius" format="dimension" />
    </declare-styleable>

public class GradientColorButton extends View {
    /**
     * 文本
     */
    private String text = "";
    /**
     * 文本颜色
     */
    private int textColor;
    /**
     * 文本大小
     */
    private float textSize;
    /**
     * 颜色的宽度
     */
    private float colorWidth;
    /**
     * 圆角度数
     */
    private float radius;
    //渐变的颜色
    private int colorStart = Color.parseColor("#E38746");
    private int color1 = Color.parseColor("#B620E0");
    private int colorEnd = Color.parseColor("#5995F6");
    //控件的宽高
    private int width;
    private int height;
    /**
     * 渐变颜色的Bitmap
     */
    private Bitmap bitmapColor;
    //画笔
    private Paint paintColor;
    private Paint paintFillet;
    private Paint paintWhite;
    private Paint paintText;
    //字体的宽高
    private int widthFont;
    private int heightFont;
    public GradientColorButton(Context context) {
        super(context);
    }
    public GradientColorButton(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs, 0);
    }
    public GradientColorButton(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        //获取参数
        TypedArray a = context.obtainStyledAttributes(attrs,
                R.styleable.GradientColorButton, defStyleAttr, 0);
        text = a.getString(R.styleable.GradientColorButton_btnText);
        textColor = a.getColor(R.styleable.GradientColorButton_btnTextColor, Color.BLACK);
        textSize = a.getDimension(R.styleable.GradientColorButton_btnTextSize, 16);
        colorWidth = a.getDimension(R.styleable.GradientColorButton_colorWidth, 5);
        radius = a.getDimension(R.styleable.GradientColorButton_colorRadius, 100);
    }
    @Override
    protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
        super.onLayout(changed, left, top, right, bottom);
        //获取View的宽高
        width = getWidth();
        height = getHeight();
        //制作一个渐变效果的Bitmap
        createGradientBitmap();
        //初始化圆角配置
        initFilletConfiguration();
        //初始化白色Bitmap配置
        initWhiteBitmapConfiguration();
        //初始化文本配置
        initTextConfiguration();
    }
    /**
     * 创建渐变颜色的Bitmap
     */
    private void createGradientBitmap() {
        //创建存放渐变效果的bitmap
        bitmapColor = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
        Canvas canvasColor = new Canvas(bitmapColor);
        LinearGradient backGradient = new LinearGradient(0, height, width, 0, new int[]{colorStart, color1, colorEnd}, null, Shader.TileMode.CLAMP);
        //绘画渐变效果
        paintColor = new Paint();
        paintColor.setShader(backGradient);
        canvasColor.drawRect(0, 0, width, height, paintColor);
    }
    /**
     * 初始化圆角配置
     */
    private void initFilletConfiguration() {
        //绘画出圆角渐变效果
        BitmapShader bitmapShaderColor = new BitmapShader(bitmapColor, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        paintFillet = new Paint();
        paintFillet.setAntiAlias(true);
        paintFillet.setShader(bitmapShaderColor);
    }
    /**
     * 初始化白色Bitmap配置
     */
    private void initWhiteBitmapConfiguration() {
        //创建存放白底的bitmap
        Bitmap bitmapWhite = Bitmap.createBitmap((int) (width - colorWidth * 2), (int) (height - colorWidth * 2), Bitmap.Config.RGB_565);
        bitmapWhite.eraseColor(Color.parseColor("#FFFFFF"));
        BitmapShader bitmapShaderWhite = new BitmapShader(bitmapWhite, Shader.TileMode.CLAMP, Shader.TileMode.CLAMP);
        // 初始化画笔
        paintWhite = new Paint();
        paintWhite.setAntiAlias(true);
        paintWhite.setShader(bitmapShaderWhite);
    }
    /**
     * 初始化文本配置
     */
    private void initTextConfiguration() {
        Rect rect = new Rect();
        paintText = new Paint();
        paintText.setAntiAlias(true);
        paintText.setColor(textColor);
        paintText.setTextSize(textSize);
        if (!TextUtils.isEmpty(text)) {
            paintText.getTextBounds(text, 0, text.length(), rect);
            widthFont = rect.width();//文本的宽度
            heightFont = rect.height();//文本的高度
        }
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        //将圆角渐变bitmap绘画到画布中
        canvas.drawRoundRect(new RectF(0, 0, width, height), radius, radius, paintFillet);
        // 将白色Bitmap绘制到画布上面
        canvas.drawRoundRect(new RectF(colorWidth, colorWidth, width - colorWidth, height - colorWidth), radius, radius, paintWhite);
        if (!TextUtils.isEmpty(text)) {
            canvas.drawText(text, (width - widthFont) / 2, (height + heightFont) / 2, paintText);
        }
    }
}

    <com.jm.xpproject.GradientColorButton
        android:layout_width="120dp"
        android:layout_height="70dp"
        android:layout_margin="10dp"
        app:btnText="收藏"
        app:btnTextColor="#123456"
        app:btnTextSize="18sp"
        app:colorRadius="50dp"
        app:colorWidth="5dp" />

什么？你连个三色渐变圆角按钮都需要UI切图？

渐变初始化电脑的后果

圆角

文本

封装

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