[英]How to draw drawable on canvas custom view in android
我正在使用音頻錄制應用程序。在錄制過程中,我像普通的音頻錄制應用程序一樣使用可視化工具。但是在特定時間想要在畫布可視化工具上繪制可繪制對象(這是自定義類,擴展View類)。
像這個白色的可繪制點。
這是我的自定義視圖類。
public class VisualizerView extends View {
private static final int LINE_WIDTH = 1; // width of visualizer lines
private static final int LINE_SCALE = 75; // scales visualizer lines
private List<VisuallizerItem> visuallizerItems; // amplitudes for line lengths
private int width; // width of this View
private int height; // height of this View
private Paint linePaint; // specifies line drawing characteristics
//Boolean isImage=false;
// constructor
public VisualizerView(Context context, AttributeSet attrs) {
super(context, attrs); // call superclass constructor
linePaint = new Paint(); // create Paint for lines
linePaint.setColor(getResources().getColor(R.color.visualizerColor)); // set color to green
linePaint.setStrokeWidth(LINE_WIDTH); // set stroke width
}
// called when the dimensions of the View change
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
width = w; // new width of this View
height = h; // new height of this View
visuallizerItems = new ArrayList<VisuallizerItem>();
}
// clear all amplitudes to prepare for a new visualization
public void clear() {
visuallizerItems.clear();
}
// add the given amplitude to the amplitudes ArrayList
public void addAmplitude(VisuallizerItem visuallizerItem) {
// isImage=false;
visuallizerItems.add(visuallizerItem); // add newest to the amplitudes ArrayList
// if the power lines completely fill the VisualizerView
if (visuallizerItems.size() * LINE_WIDTH >= width) {
visuallizerItems.remove(0); // remove oldest power value
}
}
public void addAmplitudeImage(VisuallizerItem visuallizerItem) {
//isImage=true;
visuallizerItems.add(visuallizerItem); // add newest to the amplitudes ArrayList
// if the power lines completely fill the VisualizerView
if (visuallizerItems.size() * LINE_WIDTH >= width) {
visuallizerItems.remove(0); // remove oldest power value
}
}
// draw the visualizer with scaled lines representing the amplitudes
@Override
public void onDraw(Canvas canvas) {
int middle = height / 2; // get the middle of the View
float curX = 0; // start curX at zero
// for each item in the amplitudes ArrayList
for (VisuallizerItem power : visuallizerItems) {
if (power.isImage == -100) {
float scaledHeight = power.amplitude / LINE_SCALE; // scale the power
curX += LINE_WIDTH; // increase X by LINE_WIDTH
// draw a line representing this item in the amplitudes ArrayList
canvas.drawLine(curX, middle + scaledHeight / 2, curX, middle
- scaledHeight / 2, linePaint);
} else {//**Here i'm trying to draw mark on canvas**
power.isImage = -100;
//TODO draw attachment image here
Paint p = new Paint();
Bitmap b = BitmapFactory.decodeResource(getResources(), R.drawable.yellow);
p.setColor(Color.RED);
canvas.drawBitmap(b, visuallizerItems.size(), middle, p);
}
}
}
}
該代碼一次添加白色標記,但是在再次調用onDraw時將其刪除。 其實我想在畫布上像白點上面畫一個標記。
不知道為什么將其刪除。請幫助我
提前致謝
如果在再次調用onDraw之后刪除了點,這是否與for循環的迭代方式有關?
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