如何将加载的图像以 CLI/C++ 的形式放置

Question

I have loaded an Image by CLI/C++ and i would like to display it in the form(there is Form1 turning on when running program, how to put it there). I have commented which image I would like to put in the form

// a.cpp : main project file.

#include "stdafx.h"
#include "Form1.h"
#using <mscorlib.dll> //requires CLI
using namespace System;
using namespace System::IO;
using namespace System::Windows::Media::Imaging;
using namespace System::Windows::Media;
using namespace System::Windows::Controls;
using namespace a;

[STAThreadAttribute]
int main(array<System::String ^> ^args)
{
    // Enabling Windows XP visual effects before any controls are created
    Application::EnableVisualStyles();
    Application::SetCompatibleTextRenderingDefault(false); 

    // Create the main window and run it
    Application::Run(gcnew Form1());


    // Open a Stream and decode a JPEG image
        Stream^ imageStreamSource = gcnew FileStream("C:/heart.jpg", FileMode::Open, FileAccess::Read, FileShare::Read);

        JpegBitmapDecoder^ decoder = gcnew JpegBitmapDecoder(imageStreamSource, BitmapCreateOptions::PreservePixelFormat, BitmapCacheOption::Default);
        BitmapSource^ bitmapSource = decoder->Frames[0];//< --mamy bitmape
        // Draw the Image
        System::Windows::Controls::Image^ myImage = gcnew System::Windows::Controls::Image();  //<--- this image in the Form1  -------
        myImage->Source = bitmapSource;
        myImage->Stretch = Stretch::None;
        int width = 128;
        int height = width;
        int stride = width / 8;
        array<System::Byte>^ pixels = gcnew array<System::Byte>(height * stride);

        // Define the image paletteo
        BitmapPalette^ myPalette = BitmapPalettes::Halftone256;

        // Creates a new empty image with the pre-defined palette.
        BitmapSource^ image = BitmapSource::Create(
           width, height,
           96, 96,
           PixelFormats::Indexed1,
           myPalette,
           pixels,
           stride);

        System::IO::FileStream^ stream = gcnew System::IO::FileStream("new.jpg", FileMode::Create);
        JpegBitmapEncoder^ encoder = gcnew JpegBitmapEncoder();
        TextBlock^ myTextBlock = gcnew System::Windows::Controls::TextBlock();
        myTextBlock->Text = "Codec Author is: " + encoder->CodecInfo->Author->ToString();
        encoder->FlipHorizontal = true;
        encoder->FlipVertical = false;
        encoder->QualityLevel = 30;
        encoder->Rotation = Rotation::Rotate90;
        encoder->Frames->Add(BitmapFrame::Create(image));
        encoder->Save(stream);
    return 0;
}

Answer 1

The .NET Graphics class (GDI+) is great for, well, drawing graphics. You can use it to draw not just images to a canvas, but many other things. Just google something like 'GDI+ tutorials' or '.NET Graphics', and you'll find something.

Also, the way you loaded that JPEG, there are much easier ways to do that in .NET

Answer 2

As I understand you want to show drawing in real time. For anybody that just wants to show an image in the form. Code tested for VS19. You can open an image in an image box through :

pictureBox1->Image = System::Drawing::Image::FromFile(L"C:/heart.jpg");

If you have to format the image beforehand, just save it first and then open the saved file:

System::Drawing::Image^ myImage;
//do smth
myImage->Save(L"C:/heartBUFF.jpg");
pictureBox1->Image = System::Drawing::Image::FromFile(L"C:/heartBUFF.jpg");

Answer 3

A short and therefore, partial reply, using .net 4.7.2.

I don't know about System::Windows::Media::Imaging, it just did not seem to work or be there at all.

Use System::Drawing::Imaging instead. I wanted to simply do jpeg quality and ended up with the following:

cli::array<Imaging::ImageCodecInfo^>^ imcoi = Imaging::ImageCodecInfo::GetImageEncoders(); int j;
for (j = 0; j < imcoi->Length; ++j)
{ if (imcoi[j]->MimeType == "image/jpeg") break; }
assert(j < imcoi->Length);
Imaging::ImageCodecInfo^ myImCodecInf = imcoi[j];
Imaging::Encoder^ myenc = Imaging::Encoder::Quality;
Imaging::EncoderParameters^ myencparams = gcnew Imaging::EncoderParameters(1);
Imaging::EncoderParameter^ myencparam = gcnew Imaging::EncoderParameter(myenc,95LL);
myencparams->Param[0] = myencparam;
img->Save(refstring(fn), myImCodecInf, myencparams);

hope it helps, if still needed, of course. There is a gotcha in that the quality param (here 95) must be long long, simply long is not an option and the other possibilities (unsigned char and short) just do not work.