先看效果圖：

效果圖.png

分析這是線性漸變色，圓弧半徑剛好是高度的一半翁狐，文字居中處理，大小凌蔬，顏色可調(diào)
首先開始自定義控件的基本步驟
1露懒、style自定義屬性

<!--自定義控件屬性-->
<declare-styleable name="MyGradientRoundButton">
    <attr name="colorStart" format="reference" />
    <attr name="colorEnd" format="reference" />
    <attr name="round" format="dimension" />
    <attr name="clickEffect" format="boolean" />
    <attr name="colorPressStart" format="reference" />
    <attr name="colorPressEnd" format="reference" />
    <attr name="btnText" format="reference" />
    <attr name="btnTextSize" format="dimension" />
    <attr name="btnTextColor" format="reference" />
</declare-styleable>

注：原本我是想還有點(diǎn)擊效果的
2、繼承view核心代碼

public class MyGradientRoundButton extends View {
private int colorStart;
private int colorEnd;
private int colorPressStart;
private int colorPressEnd;
private int colorS;
private int colorE;
private String text;
private int textColor;
private float textSize;
private float round;
private boolean clickEffect;
private RectF mBackGroundRect;
private LinearGradient backGradient;

//默認(rèn)畫筆
private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
private Paint mPaintText = new Paint();

public MyGradientRoundButton(Context context, AttributeSet attrs) {
    super(context, attrs);

    //獲取自定義屬性
    if (attrs != null) {
        TypedArray typedArray = context.obtainStyledAttributes(attrs, R.styleable.MyGradientRoundButton);
        colorStart = typedArray.getColor(R.styleable.MyGradientRoundButton_colorStart, getResources().getColor(R.color.btn_color_start));
        colorEnd = typedArray.getColor(R.styleable.MyGradientRoundButton_colorEnd, getResources().getColor(R.color.btn_color_end));
        round = typedArray.getDimension(R.styleable.MyGradientRoundButton_round, Utils.dip2px(context, 10));
        clickEffect = typedArray.getBoolean(R.styleable.MyGradientRoundButton_clickEffect, false);
        colorPressStart = typedArray.getColor(R.styleable.MyGradientRoundButton_colorPressStart, getResources().getColor(R.color.btn_color_PStart));
        colorPressEnd = typedArray.getColor(R.styleable.MyGradientRoundButton_colorPressEnd, getResources().getColor(R.color.btn_color_PEnd));
        text = typedArray.getString(R.styleable.MyGradientRoundButton_btnText);
        textColor = typedArray.getColor(R.styleable.MyGradientRoundButton_btnTextColor, getResources().getColor(R.color.black));
        textSize = typedArray.getDimension(R.styleable.MyGradientRoundButton_btnTextSize, 16);
        colorS = colorStart;
        colorE = colorEnd;
        typedArray.recycle();
    }
    //必須加砂心，否則onTouchEvent只響應(yīng)ACTION_DOWN
    setClickable(true);
    //設(shè)置抗鋸齒
    mPaint.setAntiAlias(true);
    //設(shè)置防抖動(dòng)
    mPaint.setDither(true);
    mPaint.setStyle(Paint.Style.FILL);

    mPaintText.setAntiAlias(true);
    mPaintText.setDither(true);
}


@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
    super.onSizeChanged(w, h, oldw, oldh);
    mBackGroundRect = new RectF(0, 0, w, h);
    backGradient = new LinearGradient(0, 0, w, 0, new int[]{colorS, colorE}, null, Shader.TileMode.CLAMP);
}


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

    mPaint.setShader(backGradient);
    //繪制背景 圓角矩形
    if (mBackGroundRect != null) {
        canvas.drawRoundRect(mBackGroundRect, round, round, mPaint);
    }
    //繪制文字
    mPaintText.setTextSize(textSize);
    mPaintText.setColor(textColor);
    mPaintText.setTextAlign(Paint.Align.CENTER);
    Paint.FontMetricsInt fontMetrics = mPaintText.getFontMetricsInt();
    float baseline = mBackGroundRect.top + (mBackGroundRect.bottom - mBackGroundRect.top - fontMetrics.bottom + fontMetrics.top) / 2 - fontMetrics.top;
    canvas.drawText(text, canvas.getWidth() / 2, baseline, mPaintText);

}

@Override
public boolean onTouchEvent(MotionEvent event) {
    if (clickEffect) {
        //刷新
        invalidate();
        //判斷點(diǎn)擊操作
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                colorS = colorPressStart;
                colorE = colorPressEnd;
                break;
            case MotionEvent.ACTION_MOVE:
                break;
            case MotionEvent.ACTION_UP:
                colorS = colorStart;
                colorE = colorEnd;
                break;
            case MotionEvent.ACTION_CANCEL:
                break;
        }
    }

    return super.onTouchEvent(event);
}


public void setText(String text) {
    if (!TextUtils.isEmpty(text)) {
        this.text = text;
        invalidate();
    }
}}

關(guān)鍵代碼講解：
onDraw():繪制圖形過程懈词，canvas.drawXXX()就是在繪制一層層圖層，所以drawRoundRect要在drawText之前
LinearGradient：線性漸變色
RectF：正方形辩诞，配合drawRoundRect就可以畫出帶圓角的圖形
onSizeChanged()：發(fā)生在onDraw()之前坎弯，一般可以做些不變的參數(shù)設(shè)定，調(diào)用onDraw(),它也不調(diào)用的
invalidate()：每調(diào)一次，也就調(diào)用了一次onDraw()方法荞怒，這樣就可以做點(diǎn)擊效果了

3、引用列子

<com.yiban1314.yiyue.widge.MyGradientRoundButton
    android:id="@+id/dialog_guide_reg"
    android:layout_width="match_parent"
    android:layout_height="@dimen/d80px"
    app:clickEffect="false"
    app:round="@dimen/d40px"
    app:colorStart="@color/btn_color_start"
    app:colorEnd="@color/btn_color_end"
    app:btnText="@string/register"
    app:btnTextColor="@color/c_22"
    app:btnTextSize="@dimen/s32px"
    android:layout_marginBottom="@dimen/d64px"
    android:layout_marginTop="@dimen/d64px"/>

這個(gè)自定義控件有個(gè)缺陷寬高不能用wrap_content屬性秧秉。