Android实现打折控件(左上角显示折扣)

• 作者:Mr.Egg
• 状态:未完成
• 转载请注明，虽然写的不好但是最少让我知道下

简单的商品打折控件实现

首先，上效果图

效果图.png

那么问题来了，怎么实现

首先分析，这个肯定要自定义View实现。与这个最像的肯定是TextView。
继承于TextView(同样可用于ImageView，这里只是测试使用不然应该用ImageView，因为内容应该是图片)
接着是绘制界面(阴影是用来显示倒计时的，暂时没用到所以不做解释)
要实现斜着的长条，首先绘制一条横向矩形

Paste_Image.png

然后沿着白色矩形左下角顶点逆时针旋转(设为335°)

旋转后

显然左上角过小，向右平移最后绘上文字(记得计算距离长度，用于适配)

效果图

最后，附上代码：

  package microcloud.org.cn.testhelloworld;

import android.annotation.TargetApi;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.os.Build;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.TextView;

/**
 * Created by Mr.Egg on 2016/11/19.
 */
public class FuckView extends TextView {

    private int defaultRotate = 315;
    private String labelText = "default";
    private int labelColor = Color.WHITE;
    private int textColor = Color.BLACK;

    public FuckView(Context context) {
        super(context);
    }

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

    public FuckView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    @TargetApi(Build.VERSION_CODES.LOLLIPOP)
    public FuckView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        int width = getMeasuredWidth();
        int height = getMeasuredHeight();


        //draw a translucent in top
        Paint timPaint = new Paint();
        timPaint.setColor(Color.parseColor("#30000000"));
        timPaint.setStyle(Paint.Style.FILL);
        canvas.drawRect(0f, 0f, width, height / 2f, timPaint);

        //draw a left mark
        Paint discountPaint = new Paint();
        discountPaint.setColor(labelColor);
        discountPaint.setStyle(Paint.Style.FILL);
        canvas.rotate(defaultRotate, 0, height / 2 + height / 8);
        canvas.translate(0, height / 8);
        Rect rect = new Rect(0, height / 4, width, height / 2);
        canvas.drawRect(rect, discountPaint);

        //draw the left mark text
        Paint textPaint = new Paint();
        textPaint.setColor(textColor);
        textPaint.setTextAlign(Paint.Align.LEFT);
        textPaint.setTextSize(rect.height() / 2);
        canvas.drawText(labelText, rect.left + height / 7, height / 2 - rect.bottom / 7, textPaint);

    }

    public FuckView retateView(int rotate) {
        this.defaultRotate = rotate;
        return this;
    }

    public FuckView setLabelText(String str) {
        this.labelText = str;
        return this;
    }

    public FuckView setLabelColor(int labelColor) {
        this.labelColor = labelColor;
        return this;
    }
    public FuckView setLabelTextColor(int textColor) {
        this.textColor = textColor;
        return this;
    }
}