然后重点就是onDraw这个方法了：
// 画自定义的渐变条
mPaint = new Paint();
// 去除锯齿
mPaint.setAntiAlias(true);
// 自定义圆角的弧度
int round = mHeight / 20;
// 新建矩形
RectF rectBg = new RectF(bmiwidth, mHeight - (mHeight * 1 / 2), mWidth
+ bmiwidth, mHeight - (mHeight * 2 / 5));
// 设置渐变色
// CLAMP重复最后一个颜色至最后
// MIRROR重复着色的图像水平或垂直方向已镜像方式填充会有翻转效果
// REPEAT重复着色的图像水平或垂直方向
LinearGradient shader = new LinearGradient(bmiwidth, mHeight
- (mHeight * 1 / 2), mWidth + bmiwidth, mHeight
- (mHeight * 2 / 5), SECTION_COLORS, null,
Shader.TileMode.MIRROR);
mPaint.setShader(shader);
// rect：RectF对象。x方向上的圆角半径。ry：y方向上的圆角半径。paint：绘制时所使用的画笔。
canvas.drawRoundRect(rectBg, round, round, mPaint);
// 画下面的小箭头
drawablePaint = new Paint();
drawablePaint.setAntiAlias(true);
Bitmap arrowBitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.arrow_up);
canvas.drawBitmap(arrowBitmap, mWidth * 2 / 17 + bmiwidth, mHeight
- (mHeight * 2 / 5) + 5, drawablePaint);
canvas.drawBitmap(arrowBitmap, mWidth * 7 / 17 + bmiwidth, mHeight
- (mHeight * 2 / 5) + 5, drawablePaint);
canvas.drawBitmap(arrowBitmap, mWidth * 12 / 17 + bmiwidth, mHeight
- (mHeight * 2 / 5) + 5, drawablePaint);
// 画下方的文字
String text = "偏瘦";
Rect textBounds = new Rect();
textPaint = new Paint();
textPaint.setAntiAlias(true);
textPaint.setColor(Color.GRAY);
textPaint.setTextSize(30);
// 获取字体的高宽
textPaint.getTextBounds(text, 0, text.length(), textBounds);
float textWidth = textBounds.width();
float textHeight = textBounds.height();
canvas.drawText("偏瘦", (mWidth * 2 / 17) / 2 - textWidth / 2 + bmiwidth,
mHeight * 7 / 10 + textHeight / 2 + 10, textPaint);
canvas.drawText("标准", (mWidth * 2 / 17) + (mWidth * 5 / 17) / 2
- textWidth / 2 + bmiwidth, mHeight * 7 / 10 + textHeight / 2
+ 10, textPaint);
canvas.drawText("超重", (mWidth * 7 / 17) + (mWidth * 5 / 17) / 2
- textWidth / 2 + bmiwidth, mHeight * 7 / 10 + textHeight / 2
+ 10, textPaint);
canvas.drawText("肥胖", (mWidth * 12 / 17) + (mWidth * 5 / 17) / 2
- textWidth / 2 + bmiwidth, mHeight * 7 / 10 + textHeight / 2
+ 10, textPaint);
// 画上方偏移的小方块
drawableBMIPaint = new Paint();
drawableBMIPaint.setAntiAlias(true);
// 设置颜色
// 通过BMI来RGB计算颜色
i = (value - 18) * (34 / 17);
if (i >= 0 && i <= 17) {
x = (int) ((17 - i) * (255 / 17));
y = 204;
z = 47;
}
if (i > 17 && i <= 34) {
x = (int) ((i - 17) * (255 / 17));
y = (int) ((34 - i) * (255 / 17));
z = 0;
}
drawableBMIPaint.setColor(Color.rgb(x, y, z));
System.out.println("颜色值为" + String.valueOf(x) + String.valueOf(y)
+ String.valueOf(z));
canvas.drawRect(getvalue(), mHeight / 6, getvalue() + bmiBitmap.getWidth(),
bmiBitmap.getHeight()+mHeight / 6, drawableBMIPaint);
System.out.println("偏移量为" + getvalue());
canvas.drawBitmap(bmiBitmap, getvalue(), mHeight / 6, drawablePaint);
// 画上方偏移的小方块里面的文字
String bmitext = "40.0";
Rect bmitextBounds = new Rect();
bmiTextpaint = new Paint();
bmiTextpaint.setAntiAlias(true);
bmiTextpaint.setTextSize(35);
bmiTextpaint.setColor(Color.WHITE);
// 获取字体的高宽
bmiTextpaint.getTextBounds(bmitext, 0, bmitext.length(), bmitextBounds);
canvas.drawText(bmiText, getvalue() - (bmitextBounds.width() / 2)
+ bmiwidth, mHeight / 3 + (bmitextBounds.height() / 3),
bmiTextpaint);
