实现的效果我一会贴上，我先说下原理，我们知道要实现在canvas上画线，不就是要搞一个paint嘛，然后首先肯定要设置下paint的属性，那么画文字呢，不就是Textpaint吗，
对，就是这么简单，接下来怎么画，折线图主要分为X轴和y轴，x轴表示日期，y表示收益，好，说道这里，大家应该知道怎么去做了，下面直接贴代码，
这个方法是，画x,y坐标系的，以及上面的日期和收益了
private void drawCoordinate(Canvas canvas) { //坐标系画笔 Paint coordinatePaint = new Paint(); coordinatePaint.setAntiAlias(true); coordinatePaint.setStrokeWidth(1); coordinatePaint.setColor(getResources().getColor(R.color.c5)); //坐标系文字画笔 TextPaint coordinateTextPaint = new TextPaint(); coordinateTextPaint.setAntiAlias(true); coordinateTextPaint.setTextSize(scaleTextSize); coordinateTextPaint.setAntiAlias(true); coordinateTextPaint.setColor(scaleTextColor); coordinateTextPaint.setTextAlign(Align.CENTER); //水平的刻度线 float verticalScaleStep = getVerticalScaleStep(); coordinateTextPaint.setTextAlign(Align.RIGHT); float textHeight = getTextHeight(coordinateTextPaint, "8"); for (int i = 0; i < maxVerticalScaleValue; i++) { float y = getHeight() - bottomPadding - (verticalScaleStep * i); canvas.drawLine(leftPadding, y, getWidth() - rightPadding, y, coordinatePaint); canvas.drawText(i + "", leftPadding - 13, y + textHeight / 2, coordinateTextPaint); } //垂直的刻度线 float horizontalScaleStep = getHorizontalScaleStep(); for (int i = 0; i < line.getSize(); i++) { float x = leftPadding + (horizontalScaleStep * i); if (i == 0) { canvas.drawLine(x, topPadding, x, getHeight() - bottomPadding, coordinatePaint); } coordinateTextPaint.setColor(mTouchIndex == i ? verticalLineColor : scaleTextColor); coordinateTextPaint.setTextAlign(i == 0 ? Align.LEFT : Align.CENTER); canvas.drawText(line.getPoint(i).getX(), x, getHeight() - bottomPadding + textHeight + 10, coordinateTextPaint); } }
但是产品有个需求啊，就是点击当前日期可以查看我的收益，并且在交汇点上展示出来
private void drawCurve(Canvas canvas) { Paint curvePaint = new Paint();//曲线画笔 curvePaint.setColor(curveColor); curvePaint.setAntiAlias(true); curvePaint.setStrokeWidth(curveStrokeWidth); float horizontalScaleStep = getHorizontalScaleStep(); float lastXPixels = 0, newYPixels = 0; float lastYPixels = 0, newXPixels = 0; float useHeight = getHeight() - bottomPadding - topPadding; for (int i = 0; i < line.getSize(); i++) { float yPercent = line.getPoint(i).getY() / maxVerticalScaleValue; if (i == 0) { lastXPixels = leftPadding + i * horizontalScaleStep; lastYPixels = getHeight() - bottomPadding - useHeight * yPercent; } else { newXPixels = leftPadding + i * horizontalScaleStep; newYPixels = getHeight() - bottomPadding - useHeight * yPercent; canvas.drawLine(lastXPixels, lastYPixels, newXPixels, newYPixels, curvePaint); lastXPixels = newXPixels; lastYPixels = newYPixels; } line.getPoint(i).fLineX = lastXPixels; line.getPoint(i).fLineY = lastYPixels; } }
点击交汇点，有文字提示说明，
private void drawTipRect(Canvas canvas) { if (mTouchIndex == -1) return; LinePoint point = line.getPoint(mTouchIndex); float x = point.fLineX; float y = point.fLineY; // 描绘竖线 Paint paint = new TextPaint(); PathEffect effects = new DashPathEffect(new float[]{5, 5, 5, 5}, 1); paint.setPathEffect(effects); paint.setAntiAlias(true); paint.setStrokeWidth(verticalLineStrokeWidth); paint.setColor(verticalLineColor); canvas.drawLine(x, topPadding, x, getHeight() - bottomPadding, paint); //描绘交汇圆点 paint.setPathEffect(null); paint.setStyle(Paint.Style.FILL_AND_STROKE); paint.setColor(Color.WHITE); canvas.drawCircle(x, y, circleRadius, paint); paint.setStyle(Paint.Style.STROKE); paint.setColor(circleColor); paint.setStrokeWidth(circleStrokeWidth); canvas.drawCircle(x, y, circleRadius, paint); float midY = (topPadding + getHeight() - bottomPadding) / 2; float midX = (leftPadding + getWidth() - rightPadding) / 2; //描绘圆角矩形 TextPaint textPaint = new TextPaint(); textPaint.setTextSize(tipTextSize); textPaint.setTextAlign(Align.CENTER); textPaint.setColor(tipTextColor); textPaint.setAntiAlias(true); String label = tipPrefix + point.getY(); float textWidth = textPaint.measureText(label) + 15; float textHeight = getTextHeight(textPaint, label) + 8; float hMargin = 10;//水平间距 float vMargin = 8;//垂直间距 float w = textWidth + hMargin * 2;//宽 float h = textHeight + vMargin * 2;//高 RectF rect = new RectF(); if (x > midX) { rect.right = x - hMargin; rect.left = x - w; } else { rect.left = x + hMargin; rect.right = x + w; } if (y > midY) { rect.top = y - h; rect.bottom = y - vMargin; } else { rect.bottom = y + h; rect.top = y + vMargin; } Paint roundRectPaint = new Paint(); roundRectPaint.setColor(tipRectColor); roundRectPaint.setStyle(Paint.Style.FILL); roundRectPaint.setAntiAlias(true); canvas.drawRoundRect(rect, 3, 3, roundRectPaint); // 描绘圆角矩形中间的文字 float roundTextX = (rect.left + rect.right) / 2; float roundTextY = (rect.top + rect.bottom + getTextHeight(textPaint, label)) / 2; canvas.drawText(label, roundTextX, roundTextY, textPaint); }好了核心的代码就这么多了，由于我们把它当做的是控件再用，那么我们在初始化的时候，肯定会引入一些自定义的样式表，
private void initViews(AttributeSet attrs, int defStyle) { TypedArray typedArray = getContext().obtainStyledAttributes(attrs, R.styleable.LineGraph, defStyle, 0); scaleTextSize = typedArray.getDimension(R.styleable.LineGraph_scale_text_size, 20); scaleTextColor = typedArray.getColor(R.styleable.LineGraph_scale_text_color, getResources().getColor(R.color.c5)); tipRectColor = typedArray.getColor(R.styleable.LineGraph_tip_rect_color, getResources().getColor(R.color.c8)); tipTextSize = typedArray.getDimension(R.styleable.LineGraph_tip_text_size, 22); tipTextColor = typedArray.getColor(R.styleable.LineGraph_tip_text_color, getResources().getColor(R.color.c12)); curveStrokeWidth = typedArray.getDimension(R.styleable.LineGraph_curve_stroke_width, 4); curveColor = typedArray.getColor(R.styleable.LineGraph_curve_color, getResources().getColor(R.color.c8)); verticalLineStrokeWidth = typedArray.getDimension(R.styleable.LineGraph_vertical_line_stroke_width, 2); verticalLineColor = typedArray.getColor(R.styleable.LineGraph_vertical_line_color, getResources().getColor(R.color.c8)); circleStrokeWidth = typedArray.getDimensionPixelSize(R.styleable.LineGraph_circle_stroke_width, 3); circleColor = typedArray.getColor(R.styleable.LineGraph_circle_color, getResources().getColor(R.color.c8)); circleRadius = typedArray.getDimensionPixelSize(R.styleable.LineGraph_circle_radius, 7); typedArray.recycle(); bottomPadding = dip2px(getContext(), 20); topPadding = dip2px(getContext(), 10); leftPadding = dip2px(getContext(), 20); rightPadding = dip2px(getContext(), 10); }
样式表文件我就不多说了，行如下面的格式，
<declare-styleable name="LineGraph"> <attr name="scale_text_size" format="dimension" /> <attr name="scale_text_color" format="color" /> <attr name="tip_text_size" format="dimension" /> <attr name="tip_text_color" format="color" /> <attr name="tip_rect_color" format="color" /> <attr name="curve_stroke_width" format="dimension" /> <attr name="curve_color" format="color" /> <attr name="vertical_line_stroke_width" format="dimension" /> <attr name="vertical_line_color" format="color" /> <attr name="circle_stroke_width" format="dimension" /> <attr name="circle_color" format="color" /> <attr name="circle_radius" format="dimension" /> </declare-styleable>
最后贴上个效果图，有需要的联系我吧，欢迎留言
git下载地址：https://github.com/xiangzhihong/lineview
