Question

我用UIGraphicsImageRendererFormat替换UIGraphicsBeginImageContext以优化性能并使我的代码现代化。出于某种原因，UIGraphicsImageRendererFormat在我的函数中返回一个空白图像。我一定做错了！

旧功能:(工作正常）

func drawImageInRect(inputImage: UIImage, inRect imageRect: CGRect) -> UIImage {


    let renderFormat = UIGraphicsImageRendererFormat.default()
    renderFormat.opaque = true
    let renderer = UIGraphicsImageRenderer(size: self.size, format: renderFormat)

    let scaledImage = renderer.image {
        (context) in
        inputImage.draw(in: imageRect)
    }
    return scaledImage
}

新功能:(什么都不画）

public class HeadBoy extends AppCompatActivity {
public static final String SHARED_PREFS = "shareactivity";
public  static final String HEAD_BOY_ONE = "count";
public static final String HEAD_BOY_TWO = "counttwo";
public SharedPreferences sharedPreferences ;
public SharedPreferences.Editor editor;
int hb1;
int hb2;
@Override
protected void onResume() {
    hideNavigationBar();
    super.onResume();
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_head_boy);
    sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);


    final Button hbone = (Button) findViewById(R.id.hbOne);
    final Button hbtwo = (Button) findViewById(R.id.hbTwo);
    hbone.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            hb1 = hb1 + 1;
            Intent intent = new Intent(HeadBoy.this,HeadGirl.class);
            startActivity(intent);
        }
    });
    hbtwo.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            hb2 = hb2 + 1;
            Intent intent = new Intent(HeadBoy.this,HeadGirl.class);
            startActivity(intent);
        }
    });
    hideNavigationBar();
    sharedPreferences.edit();
    editor.putInt(HEAD_BOY_ONE,hb1);
    editor.putInt(HEAD_BOY_TWO,hb2);
    editor.commit();
}


  public class Results extends AppCompatActivity {
@Override
protected void onResume() {
    super.onResume();
    hideNavigationBar();
}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_results);
    SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(this);
    SharedPreferences.Editor editor = sharedPreferences.edit();
    sharedPreferences.getInt(HEAD_BOY_ONE,0);

Answer 1

问题是，在您更新的功能中，您忘记绘制self，因此您将获得原始图像所在的黑色背景。

func drawImageInRect(inputImage: UIImage, inRect imageRect: CGRect) -> UIImage {
    let renderFormat = UIGraphicsImageRendererFormat.default()
    renderFormat.opaque = true
    let renderer = UIGraphicsImageRenderer(size: self.size, format: renderFormat)

    let scaledImage = renderer.image {
        (context) in
        // Add the following missing line
        self.draw(in:(CGRect(x:0.0, y:0.0, width:self.size.width, height:self.size.height)))
        inputImage.draw(in: imageRect)
    }
    return scaledImage
}

Swift：UIGraphicsImageRendererFormat而不是UIGraphicsBeginImageContext返回空白图像

1 个答案: