使用Android在画布上添加图像
我刚接触安卓java,在网上搜索了很长时间后,我真的不知道如何让按钮出现在我的视图上。我可以在布局中看到我的按钮,但调试时无法在视图中看到。我不确定在单击按钮后如何放入多个图像。如果我的代码中有错误,请纠正我。 任何帮助都将不胜感激。谢谢 我的代码如下所示:使用Android在画布上添加图像,android,android-layout,android-intent,android-widget,Android,Android Layout,Android Intent,Android Widget,我刚接触安卓java,在网上搜索了很长时间后,我真的不知道如何让按钮出现在我的视图上。我可以在布局中看到我的按钮,但调试时无法在视图中看到。我不确定在单击按钮后如何放入多个图像。如果我的代码中有错误,请纠正我。 任何帮助都将不胜感激。谢谢 我的代码如下所示: package com.example.oncanvas; import android.app.Activity; public class Main extends Activity { @Override
package com.example.oncanvas;
import android.app.Activity;
public class Main extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
DrawView DrawView = new DrawView(this);
DrawView.setBackgroundColor(Color.WHITE);
setContentView(DrawView);
DrawView.requestFocus();
}
public class DrawView extends View {
private Bitmap mBitmap;
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
private Paint mPaint;
public DrawView(Context c) {
super(c);
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(0xFF000000);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(3);
}
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX)/2, (y + mY)/2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
public void clear(){
mBitmap.eraseColor(Color.TRANSPARENT);
invalidate();
System.gc();
}}
}
这是用于布局的XML
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:id="@+id/linearLayout"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="@drawable/ic_launcher"
>
<Button
android:text="Button"
android:id="@+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</Button>
<com.example.oncanvas
android:id="@+id/drawView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
</com.example.oncanvas>
</LinearLayout>
这只是一个线索..添加您的代码
@Override
public boolean draw(Canvas canvas, MapView mapView, boolean shadow, long when) {
super.draw(canvas, mapView, shadow);
// convert point to pixels
Point screenPts = new Point();
mapView.getProjection().toPixels(pointToDraw, screenPts);
// add marker
Bitmap bmp = BitmapFactory.decodeResource(getResources(), R.drawable.marker);
canvas.drawBitmap(bmp, screenPts.x, screenPts.y - 24, null); // 24 is the height of image
return true;
}
}
在OnDraw()中,如果需要绘制多幅图像,应调用:
canvas.drawBitmap()多次使用不同的边距值
for(int i=0;i<4;i++){
canvas.drawBitmap(bmp, (i*5), (i*10), null)
}
for(int i=0;i添加图像或可绘制为位图(Png、Svg、矢量等)
用法示例:
Bitmap facebookIcon = createBitmap(R.drawable.facebookImage);
// now use it anywhere
imageView.setBitmapImage(facebookIcon);
canvas.drawBitmap(facebookIcon, 0, 0, null);
请确保保持纵横比,它适用于1:1的图像(均为正方形图像)谢谢您的回答!我正在处理它。无论如何,您知道我调试时在视图上看不到按钮的原因吗?检查按钮视图是否不可见
Bitmap facebookIcon = createBitmap(R.drawable.facebookImage);
// now use it anywhere
imageView.setBitmapImage(facebookIcon);
canvas.drawBitmap(facebookIcon, 0, 0, null);