Android canvas绘制柱形统计图

亦余心之所善兮，虽九死其犹未悔。这篇文章主要讲述Android canvas绘制柱形统计图相关的知识，希望能为你提供帮助。
如今非常多应用都须要一些统计图。眼下第三方的统计图也有非常多。可是在自己看来仅仅要不是特别耽误时间还是选择用canvas自己绘制比較合理。依赖于第三方的绘制在需求上也荣easy有一定出入，并且也不easy扩展，所以自己就依据需求绘制了一些统计图，以下就是我绘制的柱状统计图，能够依据给定高和宽来自适应，不懂的地方能够留言联系我。
【Android canvas绘制柱形统计图】
首先写一个基类，将公用的模块提取出来，这也体现设计模式中的抽象工厂模式和模板模式，以下是基类，一些共同处理的代码也能够放到BaseChartView里面。可是因为时间问题，这些会后期进行优化

import java.util.ArrayList; import android.content.Context; import android.util.AttributeSet; import android.view.View; public abstract class BaseChartView extends View { protected Context context; public ChartView(Context context) { super(context); this.context= context; } public ChartView(Context context, AttributeSet attrs) { super(context, attrs); this.context= context; } public ChartView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); this.context= context; } /** 返回最大值 **/ protected double getMaxArray(ArrayList< Double> array) { if (array.size() == 0) return 0; double max = array.get(0); for (double i : array) { max = max > i ?
max : i; } return max; } /** 返回最小值 **/ protected double getMinArray(ArrayList< Double> array) { if (array.size() == 0) return 0; double min = array.get(0); for (double i : array) { min = min < i ? min : i; } return min; } protected int px2sp(float pxValue) { final float scale = context.getResources().getDisplayMetrics().density; return (int) (pxValue / scale + 0.5f); } protected int sp2px( float spValue) { final float scale = context.getResources().getDisplayMetrics().density; return (int) (spValue * scale + 0.5f); } /** * 依据手机的分辨率从 dp 的单位转成为 px(像素) */ protected int dip2px(float dpValue) { final float scale = context.getResources().getDisplayMetrics().density; return (int) (dpValue * scale + 0.5f); } }

以下就继承这个基类来进行画图了：

import java.util.ArrayList; import java.util.List; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.DashPathEffect; import android.graphics.Paint; import android.graphics.Paint.FontMetricsInt; import android.graphics.PathEffect; import android.graphics.Rect; import android.text.Layout.Alignment; import android.text.StaticLayout; import android.text.TextPaint; import android.util.AttributeSet; public class BarChartView extends BaseChartView{ private List< Double> data_total = new ArrayList< Double> (); private List< String> data_title = new ArrayList< String> (); private float margin; private Paint paint; private float total_y = 0; private float scale; private float scaleWidth; private int width; private int textSize; public BarChartView(Context context, ArrayList< Double> data_total, ArrayList< String> data_title) { super(context); this.context = context; width = getResources().getDisplayMetrics().widthPixels; this.data_total = data_total; this.data_title = data_title; total_y = (float) (getMaxArray(data_total) * 1.2); scale = width / (3 * total_y); scaleWidth = width * 9 / (20 * data_total.size() - 10); paint = new Paint(); paint.setAntiAlias(true); margin = scaleWidth; textSize = sp2px( 9); } public BarChartView(Context context, AttributeSet attrs) { super(context, attrs); width = getResources().getDisplayMetrics().widthPixels; this.context = context; paint = new Paint(); paint.setAntiAlias(true); } public void setData(ArrayList< Double> data_total, ArrayList< String> data_title) { this.data_total = data_total; this.data_title = data_title; total_y = (float) (getMaxArray(data_total) * 1.2); scale = width / (3 * total_y); scaleWidth = width * 9 / (20 * data_total.size() - 10); margin = scaleWidth; textSize = sp2px(9); invalidate(); } public void drawAxis(Canvas canvas) { // paint.setColor(Color.YELLOW) ; paint.setStrokeWidth(1); PathEffect effects = new DashPathEffect(new float[] { width / 60, width / 100, width / 50, width / 100 }, 1); paint.setPathEffect(effects); paint.setColor(Color.parseColor(" #FFD1D1D1" )); canvas.drawLine(width / 36, scale * total_y + 0.5f, width * 31 / 32, scale * total_y + 0.5f, paint); // canvas.drawLine(30, 20, 30, 300, paint) ; int x = (int) width / 20; // paint.setTextAlign(Paint.Align.CENTER); FontMetricsInt fontMetrics = paint.getFontMetricsInt(); // 转载请注明出处：http://blog.csdn.net/hursing paint.setTextSize(textSize); paint.setColor(Color.parseColor(" #00000000" )); for (int i = 0; i < data_title.size(); i++) { TextPaint textPaint = new TextPaint(); textPaint.setTextSize(textSize); textPaint.setStrokeWidth(2); textPaint.setTextAlign(Paint.Align.CENTER); String aboutTheGame = data_title.get(i); StaticLayout layout = new StaticLayout(aboutTheGame, textPaint, (int) margin * 5 / 4, Alignment.ALIGN_NORMAL, 1.0F, 0.0F, true); // canvas.translate((int) (x-margin/2),(int) (scale*total_y+5)); Rect targetRect = new Rect((int) (x - margin / 4), (int) (scale * total_y + 5), (int) (x + margin * 5 / 4), (int) (scale * total_y * 1.2 + 5)); canvas.drawRect(targetRect, paint); // canvas.drawText(i + 1 + " gg" , x, (float) (scale*total_y+20), // paint) ; int baseline = (targetRect.top - fontMetrics.bottom); textPaint.setColor(Color.parseColor(" #000000" )); canvas.translate(targetRect.centerX(), baseline); layout.draw(canvas); x += margin * 2; canvas.translate(-targetRect.centerX(), -baseline); } } public void drawChart(Canvas canvas) { // paint.setColor(Color.GREEN) ; paint.setTextAlign(Paint.Align.CENTER); float temp = width / 20; paint.setTextSize(textSize); for (int i = 0; i < data_total.size(); i++) { // chart.drawSelf(canvas, paint) ; paint.setColor(Color.parseColor(" #4f91e1" )); Rect targetRect = new Rect((int) temp, (int) (scale * (total_y - data_total.get(i))), (int) (temp + margin), (int) (scale * total_y)); if (data_total.get(i) != 0) { canvas.drawRect(targetRect, paint); } int baseline = targetRect.top - 10; paint.setColor(Color.parseColor(" #000000" )); canvas.drawText(data_total.get(i) + " " , targetRect.centerX(), baseline, paint); temp = temp + margin * 2; } } @Override public void onDraw(Canvas canvas) { canvas.drawColor(Color.WHITE); drawChart(canvas); drawAxis(canvas); } }

这里就好了