Image processing (C++ SDK) - Object Storage Service - Alibaba Cloud Documentation Center

Image processing is a scalable, secure, cost-effective, and highly reliable image processing service provided by OSS. After you upload an image to OSS, you can use simple RESTful interfaces to process the image on any Internet-connected device.

Usage notes

In this topic, the public endpoint of the China (Hangzhou) region is used. If you want to access OSS from other Alibaba Cloud services in the same region as OSS, use an internal endpoint. For more information about OSS regions and endpoints, see Regions and endpoints.
In this topic, an OSSClient instance is created by using an OSS endpoint. If you want to create an OSSClient by using custom domain names or Security Token Service (STS), see Create an OSSClient instance.

Process an image using image processing parameters

Process an image using a single image processing parameter

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize the OSS account information. */
            
    /* Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Set yourRegion to the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Region to cn-hangzhou. */
    std::string Region = "yourRegion";
    /* Specify the name of the bucket that stores the source image, for example, examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the name of the source image. If the image is not in the root directory of the bucket, include the full path, for example, exampledir/example.jpg. */
    std::string ObjectName = "exampledir/example.jpg";

     /* Initialize network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);

    /* Resize the image to a fixed width and height of 100 px and save it locally. */
    std::string Process = "image/resize,m_fixed,w_100,h_100";
    GetObjectRequest request(BucketName, ObjectName);
    request.setProcess(Process);
    auto outcome = client.GetObject(request);
    if (outcome.isSuccess()) {
    std::cout << "Image processed successfully." << std::endl;
    } else {
    std::cout << "Failed to process image. Error code: " << outcome.error().Code()
              << ", Message: " << outcome.error().Message()
              << ", RequestId: " << outcome.error().RequestId() << std::endl;
    }

    /* Release network resources. */
    ShutdownSdk();
    return 0;
}

Process an image using multiple image processing parameters

When you use multiple image processing parameters, separate them with forward slashes (/).

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize the OSS account information. */
            
    /* Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Set yourRegion to the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Region to cn-hangzhou. */
    std::string Region = "yourRegion";
    /* Specify the name of the bucket that stores the source image, for example, examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the name of the source image. If the image is not in the root directory of the bucket, include the full path, for example, exampledir/example.jpg. */
    std::string ObjectName = "exampledir/example.jpg";

     /* Initialize network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);

    /* Resize the image to a fixed width and height of 100 px, rotate it 90 degrees, and then save it locally. */
    std::string Process = "image/resize,m_fixed,w_100,h_100/rotate,90";
    GetObjectRequest request(BucketName, ObjectName);
    request.setProcess(Process);
    auto outcome = client.GetObject(request);
    if (outcome.isSuccess()) {
    std::cout << "Image processed successfully." << std::endl;
    } else {
    std::cout << "Failed to process image. Error code: " << outcome.error().Code()
              << ", Message: " << outcome.error().Message()
              << ", RequestId: " << outcome.error().RequestId() << std::endl;
    }

    /* Release network resources. */
    ShutdownSdk();
    return 0;
}

Process an image using an image style

Create an image style.
You can include multiple image processing parameters in a style to quickly perform complex image processing operations. For more information, see Image styles.

Process the image using the image style.

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize the OSS account information. */
    
    /* Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Set yourRegion to the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Region to cn-hangzhou. */
    std::string Region = "yourRegion";
    /* Specify the name of the bucket that stores the source image, for example, examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the name of the source image. If the image is not in the root directory of the bucket, include the full path, for example, exampledir/example.jpg. */
    std::string ObjectName = "exampledir/example.jpg";

     /* Initialize network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);

    /* Process the image using an image style. Set yourCustomStyleName to the name of the image style that you created in Step 1. */
    std::string Process = "style/yourCustomStyleName";
    GetObjectRequest request(BucketName, ObjectName);
    request.setProcess(Process);
    auto outcome = client.GetObject(request);
    if (outcome.isSuccess()) {
    std::cout << "Image processed successfully." << std::endl;
    } else {
    std::cout << "Failed to process image. Error code: " << outcome.error().Code()
              << ", Message: " << outcome.error().Message()
              << ", RequestId: " << outcome.error().RequestId() << std::endl;
    }
  
    /* Release network resources. */
    ShutdownSdk();
    return 0;
}

Save processed images

You can use the ImgSaveAs operation to save the image to the current bucket. The following code shows how to save a processed image:

#include <alibabacloud/oss/OssClient.h>
#include <sstream>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize the OSS account information. */
            
    /* Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Set yourRegion to the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Region to cn-hangzhou. */
    std::string Region = "yourRegion";
    /* Specify the bucket name, for example, examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the name of the source image. If the image is not in the root directory of the bucket, include the full path, for example, example/example.jpg. */
    std::string SourceObjectName = "example/example.jpg";
    /* Specify the name of the processed image. If the image is not in the root directory of the bucket, include the full path, for example, exampledir/example.jpg. */
    std::string TargetObjectName = "exampledir/example.jpg";

    /* Initialize network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);

    /* Resize the image to a fixed width and height of 100 px and save it to the current bucket. */
    std::string Process = "image/resize,m_fixed,w_100,h_100";
    std::stringstream ss;
    ss  << Process 
    <<"|sys/saveas"
    << ",o_" << Base64EncodeUrlSafe(TargetObjectName)
    << ",b_" << Base64EncodeUrlSafe(BucketName);
    ProcessObjectRequest request(BucketName, SourceObjectName, ss.str());
    auto outcome = client.ProcessObject(request);
    if (outcome.isSuccess()) {
    std::cout << "Image processed successfully." << std::endl;
    } else {
    std::cout << "Failed to process image. Error code: " << outcome.error().Code()
              << ", Message: " << outcome.error().Message()
              << ", RequestId: " << outcome.error().RequestId() << std::endl;
    }

    /* Release network resources. */
    ShutdownSdk();
    return 0;
}

Generate a signed URL for a file with image processing parameters

A signature is required when you access a private file using its URL. OSS does not support adding image processing parameters directly to a signed URL. To process a private image, you must include the image processing parameters in the signature. The following code provides an example:

#include <alibabacloud/oss/OssClient.h>
using namespace AlibabaCloud::OSS;

int main(void)
{
    /* Initialize the OSS account information. */
            
    /* Set yourEndpoint to the Endpoint of the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Endpoint to https://oss-cn-hangzhou.aliyuncs.com. */
    std::string Endpoint = "yourEndpoint";
    /* Set yourRegion to the region where the bucket is located. For example, if the bucket is in the China (Hangzhou) region, set the Region to cn-hangzhou. */
    std::string Region = "yourRegion";
    /* Specify the name of the bucket that stores the image, for example, examplebucket. */
    std::string BucketName = "examplebucket";
    /* Specify the name of the image. If the image is not in the root directory of the bucket, include the full path, for example, exampledir/example.jpg. */
    std::string ObjectName = "exampledir/example.jpg";

    /* Initialize network resources. */
    InitializeSdk();

    ClientConfiguration conf;
    conf.signatureVersion = SignatureVersionType::V4;
    /* Obtain access credentials from environment variables. Before you run this sample code, make sure that the OSS_ACCESS_KEY_ID and OSS_ACCESS_KEY_SECRET environment variables are set. */
    auto credentialsProvider = std::make_shared<EnvironmentVariableCredentialsProvider>();
    OssClient client(Endpoint, credentialsProvider, conf);
    client.SetRegion(Region);


    /* Generate a signed URL that contains image processing parameters. */
    std::string Process = "image/resize,m_fixed,w_100,h_100";
    GeneratePresignedUrlRequest request(BucketName, ObjectName, Http::Get);
    request.setProcess(Process);
    /* The maximum validity period of the URL is 32400 seconds. */
    auto outcome = client.GeneratePresignedUrl(request);
	
    if (outcome.isSuccess()) {
    std::cout << "Generated presigned URL: " << outcome.result() << std::endl;
    } else {
    std::cout << "Failed to generate presigned URL. Error code: " << outcome.error().Code()
              << ", Message: " << outcome.error().Message()
              << ", RequestId: " << outcome.error().RequestId() << std::endl;
    }
    
    /* Release network resources. */
    ShutdownSdk();
    return 0;
}

References

For more information about the parameters supported for image processing, see Image processing.
For more information about image styles, see Image styles.