Android自動(dòng)縮放上下限折線圖示例
正文
一條折線,根據(jù)最大最小值自動(dòng)縮放上下限。
- 繼承
View
- 數(shù)據(jù)使用
FloatBuffer
存儲(chǔ) - 可改變顯示窗口的大小
- 可指定坐標(biāo)軸,折線和字體顏色
AutoLineChart完整代碼
import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Rect; import android.util.AttributeSet; import android.util.Log; import android.util.TypedValue; import android.view.View; import java.nio.FloatBuffer; public class AutoLineChart extends View { private static final String TAG = "rustApp" + AutoLineChart.class.getSimpleName(); private float yMax = 1.6f; private float yMin = -1.0f; float yAxisZoomLimitMax = 1.6f; float yAxisZoomLimitMin = -1.0f; // 縮小y軸的極限值 // Y軸自動(dòng)縮放時(shí)的增減距離 float axisYPerStep = 0.1f; // 圖表線條在view頂部留出的間距 float viewYStart = 2; float axisTextSize = 10; private int onShowPointsCount = 500; // 當(dāng)前顯示的數(shù)據(jù)個(gè)數(shù) int onShowMinPoints = 100; // 至少要顯示的數(shù)據(jù)個(gè)數(shù) private int maxPoint = 9000; // 數(shù)據(jù)存儲(chǔ)最大個(gè)數(shù) // 坐標(biāo)軸線條寬度 float axisLineWid = 1f; int dataLineWid = 4; // 數(shù)據(jù)線顏色 private int dataColor = Color.parseColor("#eaffe9"); // 圖表中的背景線條顏色 private int mainBgLineColor = Color.parseColor("#535353"); // 坐標(biāo)軸顏色 private int axisColor = Color.WHITE; // 坐標(biāo)值字體顏色 private int axisTextColor = Color.WHITE; // 背景色 private int viewBgColor = Color.parseColor("#222222"); Rect rectText = new Rect(); private float xStep = 1.0f; private float viewWidth; private float viewHeight; private float botLeftXOnView = 0; // 圖表左下點(diǎn)在view中的x坐標(biāo) private float botLeftYOnView = 0; private float originYToBottom = 20; // 圖表原點(diǎn)距離view底部的距離 private FloatBuffer dataBuffer; private Paint bgPaint; private Paint linePaint; public AutoLineChart(Context context) { this(context, null); } public AutoLineChart(Context context, AttributeSet attrs) { this(context, attrs, 0); } public AutoLineChart(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); init(context); } public int getMaxPoint() { return maxPoint; } public void setOnShowPointsCount(int onShowPointsCount) { this.onShowPointsCount = onShowPointsCount; } public int getOnShowPointsCount() { return onShowPointsCount; } public int getOnShowMinPoints() { return onShowMinPoints; } public void addData(float data) { dataBuffer.put(data); if (dataBuffer.position() > (dataBuffer.capacity() * 2 / 3)) { float[] bufferArr = dataBuffer.array(); System.arraycopy(bufferArr, dataBuffer.position() - maxPoint, bufferArr, 0, maxPoint); dataBuffer.position(maxPoint); // Log.d(TAG, "把當(dāng)前數(shù)據(jù)移動(dòng)到buffer起始位置 " + dataBuffer); } invalidate(); } private void init(Context context) { dataBuffer = FloatBuffer.allocate(3 * maxPoint); // 分配3倍的空間 bgPaint = new Paint(Paint.ANTI_ALIAS_FLAG); linePaint = new Paint(Paint.ANTI_ALIAS_FLAG); bgPaint.setStrokeWidth(axisLineWid); bgPaint.setStyle(Paint.Style.STROKE); bgPaint.setColor(mainBgLineColor); linePaint.setStrokeWidth(dataLineWid); linePaint.setStyle(Paint.Style.STROKE); linePaint.setColor(dataColor); botLeftXOnView = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 32, context.getResources().getDisplayMetrics()); originYToBottom = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 20, context.getResources().getDisplayMetrics()); viewYStart = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 20, context.getResources().getDisplayMetrics()); axisLineWid = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 1, context.getResources().getDisplayMetrics()); axisTextSize = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP, 10, context.getResources().getDisplayMetrics()); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); viewWidth = getWidth(); viewHeight = getHeight(); botLeftYOnView = viewHeight - originYToBottom; } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawColor(viewBgColor); xStep = (viewWidth - botLeftXOnView) / (onShowPointsCount - 1); float maxData = 0.1f; float minData = 0; int dataStartIndexInBuffer = 0; // 數(shù)據(jù)在buffer中的起始下標(biāo) if (dataBuffer.position() > onShowPointsCount) { dataStartIndexInBuffer = dataBuffer.position() - onShowPointsCount; } float[] bufferArr = dataBuffer.array(); for (int i = dataStartIndexInBuffer; i < dataBuffer.position(); i++) { if (bufferArr[i] < minData) { minData = bufferArr[i]; } else if (bufferArr[i] > maxData) { maxData = bufferArr[i]; } } zoomYAxis(maxData, minData); drawBgLines(canvas); drawWave(canvas, dataStartIndexInBuffer); } // 縮放Y軸 private void zoomYAxis(float maxData, float minData) { if (maxData < yAxisZoomLimitMax) { yMax = yAxisZoomLimitMax; } else if (maxData < yMax) { while (maxData < yMax) { yMax -= axisYPerStep; } yMax += axisYPerStep; } else if (maxData > yMax) { while (maxData > yMax) { yMax += axisYPerStep; } } if (minData > yAxisZoomLimitMin) { yMin = yAxisZoomLimitMin; } else if (minData > yMin) { while (minData > yMin) { yMin += axisYPerStep; } yMin -= axisYPerStep; } else if (minData < yMin) { yMin -= axisYPerStep; } } private void drawBgLines(Canvas canvas) { // 畫(huà)坐標(biāo)軸 bgPaint.setStyle(Paint.Style.FILL); bgPaint.setStrokeWidth(axisLineWid); bgPaint.setTextSize(axisTextSize); bgPaint.setTextAlign(Paint.Align.RIGHT); for (float y = 0; y <= yMax; y += 0.5) { drawYAxis(canvas, y); } for (float y = 0; y >= yMin; y -= 0.5) { drawYAxis(canvas, y); } bgPaint.setColor(axisColor); canvas.drawLine(botLeftXOnView, viewYStart / 2, botLeftXOnView, botLeftYOnView + viewYStart / 2, bgPaint); // canvas.drawLine(botLeftXOnView, botLeftYOnView, viewWidth, botLeftYOnView, bgPaint); // x軸 } private void drawYAxis(Canvas canvas, float axisYValue) { final float yDataRange = yMax - yMin; final float yAxisRangeOnView = botLeftYOnView - viewYStart; float aY = botLeftYOnView - (axisYValue - yMin) / yDataRange * yAxisRangeOnView; bgPaint.setColor(axisColor); canvas.drawLine(botLeftXOnView - 20, aY, botLeftXOnView, aY, bgPaint); String axisText = String.valueOf(axisYValue); bgPaint.getTextBounds(axisText, 0, axisText.length(), rectText); // 獲取文本的寬高 canvas.drawText(axisText, botLeftXOnView - rectText.width() / 2, aY + rectText.height() / 2, bgPaint); bgPaint.setColor(mainBgLineColor); canvas.drawLine(botLeftXOnView, aY, viewWidth, aY, bgPaint); } private void drawWave(Canvas canvas, int dataStartIndexInBuffer) { final float yDataRange = yMax - yMin; final float yAxisRangeOnView = botLeftYOnView - viewYStart; final float yDataStep = yAxisRangeOnView / yDataRange; float[] dataArr = dataBuffer.array(); for (int i = dataStartIndexInBuffer; i < dataBuffer.position() - 1; i++) { canvas.drawLine(botLeftXOnView + (i - dataStartIndexInBuffer) * xStep, getYL(dataArr[i], yDataStep), botLeftXOnView + (i - dataStartIndexInBuffer + 1) * xStep, getYL(dataArr[i + 1], yDataStep), linePaint); } } private float getYL(final float yData, float yDataStep) { return botLeftYOnView - (yData - yMin) * yDataStep; } }
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