在自定义视图中获取 xml 中 "onDraw" 的上下文

Question

我想在 onDraw 方法中从 url 加载图像以进行视图预览。我试着用毕加索来做这个。但是，我在 xml 中遇到错误。这是onDraw方法。

@Override
    protected void onDraw(Canvas canvas) {
        this.canvas = canvas;
        Picasso.get()
                .load(currentUrl)
                .into(new Target() {
                    @Override
                    public void onBitmapLoaded(Bitmap bitmap, Picasso.LoadedFrom from) {
                        Drawable d = new BitmapDrawable(getResources(), bitmap);
                        d.draw(canvas);
                    }

                    @Override
                    public void onBitmapFailed(Exception e, Drawable errorDrawable) {
                        Paint paint = new Paint();
                        paint.setColor(Color.BLACK);
                        canvas.drawText("Error to load",getWidth() / 2, getHeight() / 2,paint);
                    }

                    @Override
                    public void onPrepareLoad(Drawable placeHolderDrawable) {

                    }
                });
    }

但是，Picasso 抱怨没有上下文可以从中加载文件。这是错误：

和正文：

java.lang.IllegalStateException: context == null
    at com.squareup.picasso.Picasso.get(Picasso.java:681)
    at com.sambhav2358.badgegeneratorlibrary.BadgeView.setLogo(BadgeView.java:189)
    at com.sambhav2358.badgegeneratorlibrary.BadgeView.init(BadgeView.java:69)
    at com.sambhav2358.badgegeneratorlibrary.BadgeView.<init>(BadgeView.java:91)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at java.base/jdk.internal.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:490)
    at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:352)
    at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:189)
    at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:149)
    at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadView(LayoutlibCallbackImpl.java:301)
    at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:417)
    at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:428)
    at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:332)
    at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:965)
    at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1127)
    at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)
    at android.view.LayoutInflater.rInflate(LayoutInflater.java:1101)
    at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1088)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:686)
    at android.view.LayoutInflater.inflate(LayoutInflater.java:505)
    at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:361)
    at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:436)
    at com.android.tools.idea.layoutlib.LayoutLibrary.createSession(LayoutLibrary.java:121)
    at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:736)
    at com.android.tools.idea.rendering.RenderTask.lambda$inflate(RenderTask.java:892)
    at com.android.tools.idea.rendering.RenderExecutor$runAsyncActionWithTimeout.run(RenderExecutor.kt:187)
    at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
    at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
    at java.base/java.lang.Thread.run(Thread.java:829)

我整个classlink是here

Answer 1

AFAIK，如果申请不是运行，则无法获得 Context 参考。

Answer 2

您尝试使用 Glide 了吗？这是另一个收费图片库。

repositories {
    mavenCentral()
}

dependencies {
    compile 'com.github.bumptech.glide:glide:3.6.1'
    compile 'com.android.support:support-v4:23.1.1'
}

尝试这样做

  private void initLocal() {
        // Charge img 
        Glide.with(this).load(URL).into(imgView);
    }

在自定义视图中获取 xml 中 "onDraw" 的上下文

Get context in xml for "onDraw" in a custom view

java

android

android-custom-view

ondraw

picasso