[英]Firemonkey TCameraComponent quality change when reactivated
I'm building a barcode reader application in Delphi 10.1 Berlin with firemonkey for Android.我正在使用适用于 Android 的 firemonkey 在 Delphi 10.1 Berlin 中构建条形码阅读器应用程序。 Based on the CameraComponent sample and using the ZXing library , it was possible to read the barcode.
基于CameraComponent 示例并使用ZXing 库,可以读取条码。
To initialize the camera, I'm using this code:要初始化相机,我使用以下代码:
procedure TfrmMain.btnOpenReaderClick(Sender: TObject);
begin
CameraComponent.Active := False;
CameraComponent.FocusMode := FMX.Media.TFocusMode.ContinuousAutoFocus;
CameraComponent.Quality := TVideoCaptureQuality.MediumQuality;
CameraComponent.Active := True;
CameraComponent.SampleBufferToBitmap(imgCamera.Bitmap, True);
end;
To scan the barcode, I'm running this:要扫描条形码,我正在运行:
procedure TfrmMain.GetImage;
var
ReadResult: TReadResult;
begin
CameraComponent.SampleBufferToBitmap(imgCamera.Bitmap, True);
if (FScanInProgress) then
Exit;
{ This code will take every 4 frames. }
inc(FFrameTake);
if (FFrameTake mod 4 <> 0) then
Exit;
ReadResult := nil;
ITask(TTask.Create(
procedure
begin
try
FScanInProgress := True;
ReadResult := FScanManager.Scan(imgCamera.Bitmap);
TThread.Synchronize(nil,
procedure
begin
try
if (ReadResult <> nil) then
begin
Label1.Text := ReadResult.text;
CameraComponent.Active := False;
end;
except
on E: Exception do
ShowMessage(E.Message);
end;
end);
finally
ReadResult.Free;
imgCamera.Bitmap.Free;
FScanInProgress := false;
end;
end)).Start;
end;
After reading the barcode, when I set CameraComponent.Active := True;
读取条码后,当我设置
CameraComponent.Active := True;
to start reading a new barcode, the CameraComponent quality is automatically set to high quality, even if the property is set as medium quality when starting the component.要开始读取新条码,CameraComponent 质量会自动设置为高质量,即使在启动组件时将该属性设置为中等质量。 This causes the preview of the camera to show at low frame rate.
这会导致相机的预览以低帧率显示。 Is there a way to set the default capture setting to medium when reactivating the CameraComponent?
重新激活 CameraComponent 时,有没有办法将默认捕获设置设置为中等?
Yes you have to setup the camera before you activate it.是的,您必须在激活相机之前对其进行设置。 Like:
喜欢:
CameraComponent1.Quality := TVideoCaptureQuality.MediumQuality;
CameraComponent1.Active := true;
btw: I only stop the camera on Android and not with IOS.顺便说一句:我只在 Android 上停止相机,而不是在 IOS 上。 That's too slow.
那太慢了。 I'll close the camera with IOS on application stop.
我将在应用程序停止时使用 IOS 关闭相机。 The canvas is not updated anymore then.
画布不再更新。
procedure TdmGetBarcodeStatus.StopCamera();
begin
CameraIsActivated := false;
{$IFDEF ANDROID}
CameraComponent1.Active := false;
{$ENDIF}
end;
Also implement the camera optimization technique in the link provided by Dave.还在 Dave 提供的链接中实现相机优化技术。 Its speeds up the camera frame rate tremendously.
它极大地加快了相机的帧速率。
For a little, I think better scan strategy you can run the image scan progress in a continuous Task.有一点,我认为更好的扫描策略可以在连续任务中运行图像扫描进度。
This is how it can be done:这是如何做到的:
FParseImagesInProgress is a flag which controls the parsing of the images coming from a TRectangle (RectImage.Fill.Bitmap.Bitmap). FParseImagesInProgress 是一个标志,它控制来自 TRectangle (RectImage.Fill.Bitmap.Bitmap) 的图像的解析。 Before you stop the camera you set FParseImagesInProgress to false.
在停止相机之前,将 FParseImagesInProgress 设置为 false。
procedure TFormCamera.StartParseImageTaskService();
var
ReadResult: TReadResult;
begin
if FParseImagesInProgress then
Exit;
FParseImagesInProgress := true;
TTask.Run(
procedure
var
hints: TDictionary<TDecodeHintType, TObject>;
PossibleFormats: TList<TBarcodeFormat>;
ScanManager: TScanManager;
scanBitmap: TBitmap;
begin
PossibleFormats := TList<TBarcodeFormat>.Create();
PossibleFormats.Add(TBarcodeFormat.QR_CODE);
hints := TDictionary<TDecodeHintType, TObject>.Create();
hints.Add(TDecodeHintType.POSSIBLE_FORMATS, PossibleFormats);
ScanManager := TScanManager.Create(TBarcodeFormat.CODE_128, hints);
scanBitmap := TBitmap.Create();
try
while (FParseImagesInProgress) do
begin
ReadResult := nil;
try
TThread.Synchronize(nil,
procedure
begin
scanBitmap.Assign(RectImage.Fill.Bitmap.Bitmap);
end);
ReadResult := ScanManager.Scan(scanBitmap);
except
if Assigned(ReadResult) then
FreeAndNil(ReadResult);
end;
if Assigned(ReadResult) then
begin
TThread.Synchronize(nil,
procedure
begin
// PlaySound(TATSounds.Good);
MarkBarcode(ReadResult, TalphaColors.Deepskyblue);
if WasNotLastBarcodeInTimeWindow(ReadResult.Text) then
FBarcodeRequestManager.RequestBarcodeStatus(ReadResult.Text, HotMember, 'myDevice', HotUser,
HotPassword);
FLastBarcode := ReadResult.Text;
end);
FreeAndNil(ReadResult);
end;
Sleep(MS_BETWEEN_SCAN_FRAMES);
end; // while
finally
if Assigned(scanBitmap) then
scanBitmap := nil;
FreeAndNil(ScanManager);
if Assigned(PossibleFormats) then
begin
PossibleFormats.Clear;
PossibleFormats := nil;
end;
if Assigned(ReadResult) then
FreeAndNil(ReadResult);
end;
end); // end TTask
end;
It is really fast.它真的很快。
Anyway, hope it helps!总之,希望有帮助!
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