Question

我一直在寻找如何做到这一点。我可以访问我的相机和图库，将图像上传到我的数据库。但这就是我想要做的，我想在我的活动中拍摄照片，裁剪并在同一活动中添加文字，并在同一活动中以缩略图显示照片。（类似于WhatsApp）。

许多教程都显示了imageview和textview，但没有在同一个活动上显示图像。我如何实现这一目标？

Answer 1

许多教程都显示了imageview和textview，但没有在同一个活动上显示图像。我如何实现这一目标？

您可以将预览放在活动的布局中，并在拍照后压缩并显示图像（步骤如下）：

为相机预览创建预览类：

public class Preview : SurfaceView, ISurfaceHolderCallback
{
    private Android.Hardware.Camera mCamera;

    public Preview(Context context, Android.Hardware.Camera camera):base(context)
    {
        mCamera = camera;
        Holder.AddCallback(this);
        // deprecated setting, but required on Android versions prior to 3.0
        Holder.SetType(SurfaceType.PushBuffers);
    }
    public void SurfaceChanged(ISurfaceHolder holder, [GeneratedEnum] Format format, int width, int height)
    {
        // If your preview can change or rotate, take care of those events here.
        // Make sure to stop the preview before resizing or reformatting it.

        if (Holder.Surface == null)
        {
            // preview surface does not exist
            return;
        }

        // stop preview before making changes
        try
        {
            mCamera.StopPreview();
        }
        catch (Exception e)
        {
            // ignore: tried to stop a non-existent preview
        }

        // set preview size and make any resize, rotate or
        // reformatting changes here

        // start preview with new settings
        try
        {
            mCamera.SetPreviewDisplay(Holder);
            mCamera.StartPreview();

        }
        catch (Exception e)
        {
            //Deal with exception
        }
    }

    public void SurfaceCreated(ISurfaceHolder holder)
    {
       // The Surface has been created, now tell the camera where to draw the preview.
        try
        {
            mCamera.SetPreviewDisplay(Holder);
            mCamera.StartPreview();
        }
        catch (IOException e)
        {
            e.PrintStackTrace();
        }
    }

    public void SurfaceDestroyed(ISurfaceHolder holder)
    {
        // empty. Take care of releasing the Camera preview in your activity.
    }

}

准备布局以保存相机预览和图像：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >
  <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="250dp">
    <FrameLayout
    android:id="@+id/camera_preview"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:layout_weight="1"
    />
  </LinearLayout>
  <ImageView
    android:id="@+id/imgResult"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
  />
  <Button
    android:id="@+id/btnClick"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:text="Click Me"/>
</LinearLayout>

在活动中创建Camera和Preview并注册拍照回调：

public class MainActivity : Activity,IPictureCallback
{
    bool isCameraOpened;
    Preview mPreview;
    Android.Hardware.Camera mCamera;
    Button btnClick;
    FrameLayout camera_preview;
    protected override void OnCreate(Bundle bundle)
    {
        base.OnCreate(bundle);

        // Set our view from the "main" layout resource
        SetContentView (Resource.Layout.Main);
        btnClick = FindViewById<Button>(Resource.Id.btnClick);
        camera_preview = FindViewById<FrameLayout>(Resource.Id.camera_preview);
        mCamera = GetCameraInstance();
        mCamera.SetDisplayOrientation(90);
        mPreview = new Preview(this, mCamera);
        camera_preview.AddView(mPreview);
        btnClick.Click += BtnClick_Click;
    }

    private bool CheckCameraHardware()
    {
        if (this.PackageManager.HasSystemFeature(Android.Content.PM.PackageManager.FeatureCamera))
        {
            return true;
        } else
        {
            return false;
        }

    }

private void BtnClick_Click(object sender, System.EventArgs e)
{
    mCamera.TakePicture(null, null, this);
}

    private Android.Hardware.Camera GetCameraInstance()
    {
        Android.Hardware.Camera c=null;
        try
        {
            c = Android.Hardware.Camera.Open();
        }
        catch (Java.Lang.Exception e)
        {

        }

        return c;
    }

    public void OnPictureTaken(byte[] data, Android.Hardware.Camera camera)
    {
        Bitmap bitmap=BitmapFactory.DecodeByteArray(data, 0, data.Length);
        Bitmap resizedBitmap=Bitmap.CreateScaledBitmap(bitmap, 100, 100, true);
        FindViewById<ImageView>(Resource.Id.imgResult).SetImageBitmap(resizedBitmap);
        //restart the preview
        if (mCamera != null)
        {
            mCamera.StartPreview();
        }

    }
}

有关Camera API的详细使用，请参阅Camera API。

注意：不要忘记添加<uses-permission android:name="android.permission.CAMERA" />和 <uses-feature android:name="android.hardware.camera" />至AndroidManifest.xml。

Answer 2

为什么不使用HashMap存储＆＃39;文本＆＃39;作为关键＆amp; ＆＃39;图片路径＆＃39;作为它的价值。在Application类上创建它的实例。

您可以在onActivityResult（）方法上使用该HashMap。

从相机捕获图像并在相同活动中显示。 -Xamarin

2 个答案: