Se você não tem tempo para ler ou se conhece as informações, o código final para obter uma imagem em tamanho real de uma câmera de smartphone Android está localizado no final do artigo.
Descrição do problema
Se você estiver escrevendo um aplicativo de plataforma cruzada, pode usar a classe QCamera para obter uma imagem de uma câmera de PC , um exemplo que está descrito na documentação do Qt.
De acordo com o exemplo acima, adicionamos ao arquivo .pro
QT += multimedia multimediawidgets
A seguir, criamos um widget em nosso programa que exibe uma imagem de uma webcam e a salva em um QPixmap ou QImage para uso futuro.
Quando surge a tarefa de fazer o mesmo no Android, verifica-se que widgets multimídia não são suportados por este sistema operacional e a câmera vai tirar e salvar fotos, mas o que ela exibe no momento será um mistério, já que QCameraViewfinder usa widgets multimídia e não exibir nada no Android. A busca por uma solução para o problema leva a duas soluções:
use QML e escreva seu próprio Qt Quick-element que execute esta função, então encaixe-o com o resto do aplicativo em Qt Widgets , C ++;
use o aplicativo padrão do smartphone Android para receber uma foto e, em seguida, processe-a em seu aplicativo.
Considere a primeira opção
Se você é um programador C ++ de Qt Widgets , então o próximo aprofundamento episódico em QML levará seu tempo, acrescente a este tempo para escrever um elemento Qt Quick , encaixe este elemento com código C ++, depure o código escrito. Se você não é um profissional em QML, acaba sendo longo e difícil.
Considere a segunda opção
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android {
QT +=androidextras
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(.h) :
#ifndef CAMSHOT_H
#define CAMSHOT_H
#include <QObject>
#include <QString>
#include <cstring>
#include <QImage>
#include <QDebug>
#include <QtAndroid>
#include <QAndroidActivityResultReceiver>
#include <QAndroidParcel>
class CamShot : public QObject, public QAndroidActivityResultReceiver
{
Q_OBJECT
public:
CamShot(QObject *parent = nullptr):QObject(parent),QAndroidActivityResultReceiver(){}
static const int RESULT_OK = -1;
static const int REQUEST_IMAGE_CAPTURE = 1;
static const int REQUEST_TAKE_PHOTO = REQUEST_IMAGE_CAPTURE;
void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data) override;
static QImage camThumbnailToQImage(const QAndroidJniObject &data);
public slots:
void aMakeShot();
signals:
void createNew(const QImage &img);
};
#endif // CAMSHOT_H
(.cpp) :
QImage CamShot::camThumbnailToQImage(const QAndroidJniObject &data){
QAndroidJniObject bundle = data.callObjectMethod("getExtras","()Landroid/os/Bundle;");
qDebug()<<"bundle.isValid() "<<bundle.isValid()<<bundle.toString();
QAndroidJniObject bundleKey = QAndroidJniObject::fromString("data");
const QAndroidJniObject aBitmap (data.callObjectMethod("getParcelableExtra", "(Ljava/lang/String;)Landroid/os/Parcelable;", bundleKey.object<jstring>()));
qDebug()<<"aBitmap.isValid() "<<aBitmap.isValid()<<aBitmap.toString();
jint aBitmapWidth = aBitmap.callMethod<jint>("getWidth");
jint aBitmapHeight = aBitmap.callMethod<jint>("getHeight");
QAndroidJniEnvironment env;
const int32_t aBitmapPixelsCount = aBitmapWidth * aBitmapHeight;
jintArray pixels = env->NewIntArray(aBitmapPixelsCount);
jint aBitmapOffset = 0;
jint aBitmapStride = aBitmapWidth;
jint aBitmapX = 0;
jint aBitmapY = 0;
aBitmap.callMethod<void>("getPixels","([IIIIIII)V", pixels, aBitmapOffset, aBitmapStride, aBitmapX, aBitmapY, aBitmapWidth, aBitmapHeight);
jint *pPixels = env->GetIntArrayElements(pixels, nullptr);
QImage img(aBitmapWidth, aBitmapHeight, QImage::Format_ARGB32);
int lineSzB = aBitmapWidth * sizeof(jint);
for (int i = 0; i < aBitmapHeight; ++i){
uchar *pDst = img.scanLine(i);
const uchar *pSrc = reinterpret_cast<const uchar*>(pPixels + aBitmapWidth * i + aBitmapWidth);
memcpy(pDst, pSrc, lineSzB);
}
env->DeleteLocalRef(pixels); //env->ReleaseIntArrayElements(pixels, pPixels, 0); , , DeleteLocalRef.
return img;
}
void CamShot::aMakeShot() {
QAndroidJniObject action = QandroidJniObject::fromString("android.media.action.IMAGE_CAPTURE");
// Java- ( ), (- "/"), "android/content/Intent", "java/lang/String".
// Java-, "L" ";" , "Landroid/content/Intent ;", "Ljava/lang/String;".
// , , "V" (void) "[IIIIIII" ( jint, 6 jint )
//, :
QAndroidJniObject intent=QAndroidJniObject("android/content/Intent","(Ljava/lang/String;)V", action.object<jstring>());
QtAndroid::startActivity(intent, REQUEST_IMAGE_CAPTURE, this);
}
void CamShot::handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data){
if ( receiverRequestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK )
{
const QImage thumbnail (camThumbnailToQImage(data));
if (!thumbnail.isNull())
emit createNew(thumbnail);
}
}
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int8_t/char/signed char
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uint16_t/unsigned short
jchar
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int32_t/int/(long)
jint
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int64_t/(long)/long long
jlong
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float
jfloat
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double
jdouble
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void
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jbyteArray
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jcharArray
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, JNI- QAndroidJniEnvironment, : NewIntArray, GetIntArrayElements, DeleteLocalRef GetArrayLength,GetObjectArrayElement, SetObjectArrayElement, ..
(pdf) Practical Qt on Android JNI — qtcon.
class CamShot :
, Android ( Java-);
void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data) override;
Java- Intent ;
static QImage camThumbnailToQImage(const QAndroidJniObject &data);
Java- Intent Java- Bitmap, (32- ) QImage;
void aMakeShot();
;
void createNew(const QImage &img);
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void getPixels (int[] pixels, int offset, int stride, int x, int y, int width, int height)
jintArray pixels = env->NewIntArray(aBitmapPixelsCount);
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jint *pPixels = env->GetIntArrayElements(pixels, nullptr);
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env->DeleteLocalRef(pixels);
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androidx.core.content.FileProvider;
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- Android, .pro android: :
android { QT +=androidextras } # … DISTFILES += \ android: android/AndroidManifest.xml \ android: android/build.gradle \ android: android/gradle/wrapper/gradle-wrapper.jar \ android: android/gradle/wrapper/gradle-wrapper.properties \ android: android/gradlew \ android: android/gradlew.bat \ android: android/res/values/libs.xml \ todo.txt
AndroidManifest.xml
«AndroidManifest.xml» android/AndroidManifest.xml,
</activity>
<!-- For adding service(s) please check: https://wiki.qt.io/AndroidServices ->
:
<provider android:name="android.support.v4.content.FileProvider" android:authorities="org.qtproject.example.qsketch.fileprovider" android:grantUriPermissions="true" android:exported="false">
<meta-data android:name="android.support.FILE_PROVIDER_PATHS" android:resource="@xml/file_paths"/>
</provider>
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, «AndroidManifest.xml» «res» «values», «xml», «file_paths.xml» (… /abin/AndroidManifest.xml) (… /abin/res/xml/file_paths.xml). :
<?xml version="1.0" encoding="utf-8"?>
<paths xmlns:android="http://schemas.android.com/apk/res/android">
<external-files-path name="shared" path="shared/" />
</paths>
shared/
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android/build.gradle, dependencies :
compile'com.android.support:support-v4:25.3.1'
:
dependencies { implementation fileTree(dir: 'libs', include: ['*.jar', '*.aar']) compile'com.android.support:support-v4:25.3.1' }
, Android Support Repository.
Sharing Files on Android or iOS from or with your Qt App - Part 4 .
(.h) :
#ifndef CAMSHOT_H
#define CAMSHOT_H
#include <QObject>
#include <QImage>
#include <QString>
#include <QDebug>
#include <QtAndroid>
#include <QAndroidActivityResultReceiver>
#include <QAndroidParcel>
#include "auxfunc.h"
class CamShot : public QObject, public QAndroidActivityResultReceiver
{
Q_OBJECT
public:
static const int RESULT_OK = -1;
static const int REQUEST_IMAGE_CAPTURE = 1;
static const int REQUEST_TAKE_PHOTO = REQUEST_IMAGE_CAPTURE;
enum ImgOrientation {ORIENTATION_UNDEFINED = 0, ORIENTATION_NORMAL = 1, ORIENTATION_FLIP_HORIZONTAL = 2, ORIENTATION_ROTATE_180 = 3, ORIENTATION_FLIP_VERTICAL = 4, ORIENTATION_TRANSPOSE = 5,
ORIENTATION_ROTATE_90 = 6, ORIENTATION_TRANSVERSE = 7, ORIENTATION_ROTATE_270 = 8};
void handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data) override;
static QImage aBitmapToQImage(const QAndroidJniObject &aBitmap);
static QImage camThumbnailToQImage(const QAndroidJniObject &data);
ImgOrientation needRotateAtRightAngle();
QImage camImageToQImage();
static void applyOrientation(QImage &img, const ImgOrientation &orientation);
explicit CamShot(QObject *parent = nullptr):QObject(parent),QAndroidActivityResultReceiver(){}
~CamShot();
private:
QAndroidJniObject tempImgURI;
QAndroidJniObject tempImgFile;
QAndroidJniObject tempImgAbsPath;
bool _thumbnailNotFullScaleRequested;
public slots:
void aMakeShot(const bool &thumbnailNotFullScale = false);
signals:
void createNew(const QImage &img);
};
#endif // CAMSHOT_H
(.cpp) :
QImage CamShot::aBitmapToQImage(const QAndroidJniObject &aBitmap){
if (!aBitmap.isValid())
return QImage();
jint aBitmapWidth = aBitmap.callMethod<jint>("getWidth");
jint aBitmapHeight = aBitmap.callMethod<jint>("getHeight");
QAndroidJniEnvironment env;
const int32_t aBitmapPixelsCount = aBitmapWidth * aBitmapHeight;
jintArray pixels = env->NewIntArray(aBitmapPixelsCount);
jint aBitmapOffset = 0;
jint aBitmapStride = aBitmapWidth;
jint aBitmapX = 0;
jint aBitmapY = 0;
aBitmap.callMethod<void>("getPixels","([IIIIIII)V", pixels, aBitmapOffset, aBitmapStride, aBitmapX, aBitmapY, aBitmapWidth, aBitmapHeight);
jint *pPixels = env->GetIntArrayElements(pixels, nullptr);
QImage img(aBitmapWidth, aBitmapHeight, QImage::Format_ARGB32);
int lineSzB = aBitmapWidth * sizeof(jint);
for (int i = 0; i < aBitmapHeight; ++i){
uchar *pDst = img.scanLine(i);
const uchar *pSrc = reinterpret_cast<const uchar*>(pPixels + aBitmapWidth * i + aBitmapWidth);
memcpy(pDst, pSrc, lineSzB);
}
env->DeleteLocalRef(pixels); //env->ReleaseIntArrayElements(pixels, pPixels, 0); , , DeleteLocalRef.
return img;
}
QImage CamShot::camThumbnailToQImage(const QAndroidJniObject &data){
//
QAndroidJniObject bundle = data.callObjectMethod("getExtras","()Landroid/os/Bundle;");
qDebug()<<"bundle.isValid() "<<bundle.isValid()<<bundle.toString();
// jstring ( Java) "data" - <, > - Bitmap (Java)
QAndroidJniObject bundleKey = QAndroidJniObject::fromString("data");
// "data" : Bitmap
const QAndroidJniObject aBitmap (data.callObjectMethod("getParcelableExtra", "(Ljava/lang/String;)Landroid/os/Parcelable;", bundleKey.object<jstring>()));
qDebug()<<"aBitmap.isValid() "<<aBitmap.isValid()<<aBitmap.toString();
return aBitmapToQImage(aBitmap);
}
QImage CamShot::camImageToQImage(){
QAndroidJniObject bitmap = QAndroidJniObject::callStaticObjectMethod("android/graphics/BitmapFactory","decodeFile","(Ljava/lang/String;)Landroid/graphics/Bitmap;",tempImgAbsPath.object<jobject>());
qDebug()<<"bitmap.isValid() "<<bitmap.isValid()<<bitmap.toString();
QImage img = aBitmapToQImage(bitmap);
//
if (tempImgFile.isValid())
tempImgFile.callMethod<jboolean>("delete");
return img;
}
CamShot::ImgOrientation CamShot::needRotateAtRightAngle(){
//
QAndroidJniObject exifInterface = QAndroidJniObject("android/media/ExifInterface","(Ljava/lang/String;)V",
tempImgAbsPath.object<jstring>());
qDebug() << __FUNCTION__ << "exifInterface.isValid()=" << exifInterface.isValid();
QAndroidJniObject TAG_ORIENTATION = QAndroidJniObject::getStaticObjectField<jstring>("android/media/ExifInterface", "TAG_ORIENTATION");
qDebug() << __FUNCTION__ << "TAG_ORIENTATION.isValid()=" << TAG_ORIENTATION.isValid()<<TAG_ORIENTATION.toString();
const jint orientation = exifInterface.callMethod<jint>("getAttributeInt","(Ljava/lang/String;I)I",TAG_ORIENTATION.object<jstring>(),static_cast<jint>(ORIENTATION_UNDEFINED));
return static_cast<ImgOrientation>(orientation);
}
void CamShot::applyOrientation(QImage &img, const ImgOrientation &orientation){
switch (orientation){
case ORIENTATION_UNDEFINED:
case ORIENTATION_NORMAL:
break;
case ORIENTATION_FLIP_HORIZONTAL:{
img = img.mirrored(true, false);
break;
}
case ORIENTATION_ROTATE_180:
Aux::rotateImgCW180(img);
break;
case ORIENTATION_FLIP_VERTICAL:{
img = img.mirrored(false, true);
break;
}
case ORIENTATION_TRANSPOSE:{
img = img.mirrored(true, false);
Aux::rotateImgCW270(img);
break;
}
case ORIENTATION_ROTATE_90:
Aux::rotateImgCW90(img);
break;
case ORIENTATION_TRANSVERSE:{
img = img.mirrored(true, false);
Aux::rotateImgCW90(img);
break;
}
break;
case ORIENTATION_ROTATE_270:
Aux::rotateImgCW270(img);
break;
}
}
void CamShot::handleActivityResult(int receiverRequestCode, int resultCode, const QAndroidJniObject &data){
if ( receiverRequestCode == REQUEST_IMAGE_CAPTURE && resultCode == RESULT_OK )
{
if (_thumbnailNotFullScaleRequested){
const QImage thumbnail (camThumbnailToQImage(data));
if (!thumbnail.isNull())
emit createNew(thumbnail);
return;
}
const ImgOrientation orientation = needRotateAtRightAngle();
QImage image (camImageToQImage());
if (!image.isNull()){
applyOrientation(image, orientation);
emit createNew(image);
}
}
}
void CamShot::aMakeShot(const bool &thumbnailNotFullScale) {
QAndroidJniObject action = QAndroidJniObject::fromString("android.media.action.IMAGE_CAPTURE");
//
QAndroidJniObject intent=QAndroidJniObject("android/content/Intent","(Ljava/lang/String;)V",
action.object<jstring>());
qDebug() << __FUNCTION__ << "intent.isValid()=" << intent.isValid();
_thumbnailNotFullScaleRequested = thumbnailNotFullScale;
if (thumbnailNotFullScale) {
//
QtAndroid::startActivity(intent, REQUEST_IMAGE_CAPTURE, this);
return;
}
//
QAndroidJniObject context = QtAndroid::androidContext();
QString contextStr (context.toString());
qDebug() <<"Context: "<<contextStr;
//
QAndroidJniObject extDir = context.callObjectMethod("getExternalFilesDir", "(Ljava/lang/String;)Ljava/io/File;", NULL);
qDebug() << __FUNCTION__ << "extDir.isValid()=" << extDir.isValid()<<extDir.toString();
//
QAndroidJniObject extDirAbsPath = extDir.callObjectMethod("getAbsolutePath","()Ljava/lang/String;");
// . . /res/xml/file_paths.xml
extDirAbsPath = QAndroidJniObject::fromString(extDirAbsPath.toString() + "/shared");
const QString extDirAbsPathStr = extDirAbsPath.toString();
qDebug() << __FUNCTION__ << "extDirAbsPath.isValid()=" << extDirAbsPath.isValid()<<extDirAbsPathStr;
//
QAndroidJniObject sharedFolder=QAndroidJniObject("java.io.File","(Ljava/lang/String;)V",
extDirAbsPath.object<jstring>());
qDebug() << __FUNCTION__ << "sharedFolder.isValid()=" << sharedFolder.isValid()<<sharedFolder.toString();
const jboolean sharedFolderCreated = sharedFolder.callMethod<jboolean>("mkdirs");
Q_UNUSED(sharedFolderCreated);
// ,
//
QAndroidJniObject suggestedFilePath = QAndroidJniObject::fromString(extDirAbsPathStr+"/"+"_tmp.jpg");
qDebug() << __FUNCTION__ << "suggestedFilePath.isValid()=" << suggestedFilePath.isValid()<<suggestedFilePath.toString();
//
//
QAndroidJniObject tempImgFile=QAndroidJniObject("java.io.File","(Ljava/lang/String;)V",
suggestedFilePath.object<jstring>());
qDebug() << __FUNCTION__ << "fileExistsCheck.isValid()=" << tempImgFile.isValid()<<tempImgFile.toString();
// ,
if (tempImgFile.isValid()){
const jboolean deleted = tempImgFile.callMethod<jboolean>("delete");
Q_UNUSED(deleted);
}
//
const jboolean fileCreated = tempImgFile.callMethod<jboolean>("createNewFile");
Q_UNUSED(fileCreated);
//
tempImgAbsPath = tempImgFile.callObjectMethod("getAbsolutePath","()Ljava/lang/String;");
qDebug() << __FUNCTION__ << "tempImgAbsPath.isValid()=" << tempImgAbsPath.isValid()<<tempImgAbsPath.toString();
// authority fileprovider
const QString contextFileProviderStr ("org.qtproject.example.qsketch.fileprovider");
const char androidFileProvider [] = "android/support/v4/content/FileProvider";
//const char androidxFileProvider [] = "androidx/core/content/FileProvider"; - Qt
/*QAndroidJniObject*/ tempImgURI = QAndroidJniObject::callStaticObjectMethod(androidFileProvider, "getUriForFile", "(Landroid/content/Context;Ljava/lang/String;Ljava/io/File;)Landroid/net/Uri;",
context.object<jobject>(), QAndroidJniObject::fromString(contextFileProviderStr).object<jstring>(), tempImgFile.object<jobject>());
qDebug() << __FUNCTION__ << "tempImgURI.isValid()=" << tempImgURI.isValid()<<tempImgURI.toString();
// MediaStore.EXTRA_OUTPUT
QAndroidJniObject MediaStore__EXTRA_OUTPUT
= QAndroidJniObject::getStaticObjectField("android/provider/MediaStore", "EXTRA_OUTPUT", "Ljava/lang/String;");
qDebug() << "MediaStore__EXTRA_OUTPUT.isValid()=" << MediaStore__EXTRA_OUTPUT.isValid();
// URI
intent.callObjectMethod("putExtra","(Ljava/lang/String;Landroid/os/Parcelable;)Landroid/content/Intent;",MediaStore__EXTRA_OUTPUT.object<jstring>(), tempImgURI.object<jobject>());
qDebug() << __FUNCTION__ << "intent.isValid()=" << intent.isValid();
QtAndroid::startActivity(intent, REQUEST_IMAGE_CAPTURE, this);
}
- Aux .
(.h) Aux :
#ifndef AUXFUNC_H
#define AUXFUNC_H
#include <QImage>
#include <QColor>
#include <QPainter>
#include <QMatrix>
#include <QSize>
#include <QPoint>
class Aux
{
public:
static void resizeCenteredImg(QImage *image, const QSize &newSize, const QColor bgColor);
static void rotateImg(QImage &img, qreal degrees);
static void rotateImgCW90(QImage &img);
static void rotateImgCW180(QImage &img);
static void rotateImgCW270(QImage &img);
};
#endif // AUXFUNC_H
(.cpp) Aux :
void Aux::resizeCenteredImg(QImage *image, const QSize &newSize, const QColor bgColor){
if (image->size() == newSize)
return;
const QSize szDiff = newSize - image->size();
QImage newImage(newSize, QImage::Format_ARGB32);
newImage.fill(bgColor);
QPainter painter(&newImage);
painter.drawImage(QPoint(szDiff.width()/2, szDiff.height()/2), *image);
*image = newImage;
}
void Aux::rotateImg(QImage &img, qreal degrees){
QPoint center = img.rect().center();
QMatrix matrix;
matrix.translate(center.x(), center.y());
matrix.rotate(degrees);
img = img.transformed(matrix, Qt::SmoothTransformation);
}
void Aux::rotateImgCW90(QImage &img){
const int w = img.width();
const int h = img.height();
const int maxDim = std::max(w, h);
resizeCenteredImg(&img, QSize(maxDim, maxDim), Qt::white);
rotateImg(img, 90);
resizeCenteredImg(&img, QSize(h, w), Qt::white);
}
void Aux::rotateImgCW180(QImage &img){
rotateImg(img, 180);
}
void Aux::rotateImgCW270(QImage &img){
const int w = img.width();
const int h = img.height();
const int maxDim = std::max(w, h);
resizeCenteredImg(&img, QSize(maxDim, maxDim), Qt::white);
rotateImg(img, 270);
resizeCenteredImg(&img, QSize(h, w), Qt::white);
}
.
«thumbnailNotFullScale». , , , . JNI-.
Se a miniatura estiver sempre orientada corretamente, a imagem em tamanho real é direcionada em uma direção e deve ser girada. Informações sobre as transformações necessárias podem ser obtidas nas propriedades exif da imagem usando a interface Exif . Nos exemplos de Java encontrados na Internet , a conversão para a orientação normal é feita em código Java, no caso do Qt não há motivo para se torturar com chamadas JNI difíceis de depurar e incômodas, e é mais fácil executar todas as transformações necessárias em Qt.