由於移動設備屏幕通常比較小,可能不能滿足工程中整個圖形的顯示,我找了很久就是沒找到在surfaceView中實現canvas上下滾動。解決此問題我認爲有兩種思路,一種思路根據手的滑動,動態的繪製圖形,即不斷的重複清屏和繪製;另一種思路是藉助ScrollView,設置surfaceView的高寬(注意:默認情況下surfaceView的高和寬即是canvas的高和寬,也可以自己修改)。第二種思路實現起來比較簡單,本文實現了第二種思路如下:
1、圖形
2、源代碼
xml文件
<?xml version="1.0" encoding="utf-8"?>
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".SurfaceViewSlideActivity"
android:orientation="vertical">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<SurfaceView
android:id="@+id/surface_view"
android:background="#FFFFFF"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
</ScrollView>
SurfaceViewSlideActivity文件
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.DisplayMetrics;
import android.view.SurfaceView;
import android.view.ViewGroup;
public class SurfaceViewSlideActivity extends AppCompatActivity {
private SurfaceView surfaceView = null;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_surface_view_slide);
// 獲得surfaceView
this.surfaceView = findViewById(R.id.surface_view);
// 獲得屏幕的高度
DisplayMetrics metric = new DisplayMetrics();
this.getWindowManager().getDefaultDisplay().getMetrics(metric);
int height = metric.heightPixels;
// 重置SurfaceView的高度
ViewGroup.LayoutParams params = this.surfaceView.getLayoutParams();
params.height = 2*height;
SurfaceViewSlide surfaceView = new SurfaceViewSlide(this, this.surfaceView);
}
}
SurfaceViewSlide文件
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
/**
* Create by RuiAiXinAn 2019/5/22
* Class description:
*/
public class SurfaceViewSlide extends SurfaceView implements SurfaceHolder.Callback{
private SurfaceHolder surfaceHolder = null;
private Paint paint = null;
public SurfaceViewSlide(Context context, SurfaceView surfaceView) {
super(context);
this.surfaceHolder = surfaceView.getHolder();
// 設置爲透明,如果不設置爲透明,則繪製的直線不顯示
surfaceView.setZOrderOnTop(true);
this.surfaceHolder.setFormat(PixelFormat.TRANSLUCENT);
// 設置畫筆
this.paint = new Paint();
this.paint.setColor(Color.BLACK);
this.paint.setStrokeWidth(2.0f);
this.paint.setStyle(Paint.Style.STROKE);
this.paint.setAntiAlias(true);
// 添加回調
this.surfaceHolder.addCallback(this);
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
// 繪製直線
Canvas canvas = this.surfaceHolder.lockCanvas();
// 清除canvas上的圖
// this.canvas.drawColor(Color.TRANSPARENT, PorterDuff.Mode.CLEAR);
canvas.drawLine(1,1,2000,2000, this.paint);
this.surfaceHolder.unlockCanvasAndPost(canvas);
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
}
}