Windows dialog based OpenCV Perspective Transform - 윈도우 다이얼로그 기반의 OpenCV Perspective Transform

Build a windows dialog-based OpenCV perspective transform program.

Change Subsystem setting from Console to Windows if necessary.

Add a resource and create a dialog box.

Include and declare necessities.

#include <Windows.h>
#include <opencv2/opencv.hpp>
#include "resource.h"
 
using namespace cv;
 
bool getFile(PTCHAR filename);
void onMouse(int event, int x, int y, int flags, void* userdata);
INT_PTR MainDlgProc(HWND hDlg, UINT iMessage, WPARAM wParam, LPARAM lParam);
 
HWND hDlgMain;
 
Mat sourceImage;
Mat targetImage;
// TTC card ratio
int width = 850;
int height = 550;
Point2f srcQuad[4], dstQuad[4];

Define WinMain which calls getFile() and DialogBox().

int APIENTRY WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCmdParam, int nCmdShow)
{
    TCHAR filename[MAX_PATH] = "";
    if (!getFile(filename)) {
        return -1;
    }
 
    sourceImage = imread(filename);
    if (sourceImage.empty()) {
        MessageBox(NULL, TEXT("Image load failed"), TEXT("No image loaded"), MB_OK);
 
        return -1;
    }
 
    namedWindow("sourceImage");
    setMouseCallback("sourceImage", onMouse);
 
    imshow("sourceImage", sourceImage);
 
    DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG1), HWND_DESKTOP, MainDlgProc);
 
    return 0;
}

getFile() retrieves an image file.

bool getFile(PTCHAR filename)
{
    OPENFILENAME ofn;
    memset(&ofn, 0, sizeof(OPENFILENAME));
    ofn.lStructSize = sizeof(OPENFILENAME);
    ofn.hwndOwner = NULL;
    ofn.lpstrFilter = TEXT("all(*.*)\0*.*\0jpg(*.jpg)\0*.jpg\0png(*.png)\0*.png\0bmp(*.bmp)\0*.bmp\0");
    ofn.lpstrFile = filename;
    ofn.nMaxFile = MAX_PATH;
 
    if (GetOpenFileName(&ofn) != 0) {
        //MessageBox(NULL, filename, TEXT("File opened."), MB_OK);
 
        return true;
    }
    else {
        MessageBox(NULL, TEXT("File open failed"), TEXT("No file selected"), MB_OK);
 
        return false;
    }
}

Define a mouse callback function that processes perspective transform.

void onMouse(int event, int x, int y, int flags, void* userdata)
{
    static int cnt = 0;
 
    if (event == EVENT_LBUTTONDOWN) {
        if (cnt < 4) {
            srcQuad[cnt++] = Point2f(x, y);
 
            circle(sourceImage, Point2f(x, y), 3, Scalar(0, 0, 255), -1);
            imshow("sourceImage", sourceImage);
 
            if (cnt == 4) {
                /*
                width = max(
                    sqrt(pow(srcQuad[0].x - srcQuad[1].x, 2)) + sqrt(pow(srcQuad[0].y - srcQuad[1].y, 2)),
                    sqrt(pow(srcQuad[2].x - srcQuad[3].x, 2)) + sqrt(pow(srcQuad[2].y - srcQuad[3].y, 2))
                );
                height = max(
                    sqrt(pow(srcQuad[1].x - srcQuad[2].x, 2)) + sqrt(pow(srcQuad[1].y - srcQuad[2].y, 2)),
                    sqrt(pow(srcQuad[3].x - srcQuad[0].x, 2)) + sqrt(pow(srcQuad[3].y - srcQuad[0].y, 2))
                );
                */            
 
                dstQuad[0] = Point2f(0, 0);
                dstQuad[1] = Point2f(width - 1, 0);
                dstQuad[2] = Point2f(width - 1, height - 1);
                dstQuad[3] = Point2f(0, height - 1);
 
                Mat perspectiveTransform = getPerspectiveTransform(srcQuad, dstQuad);
 
                warpPerspective(sourceImage, targetImage, perspectiveTransform, Size(width, height));
 
                cnt = 0;
                
                imshow("targetImage", targetImage);
            }
        }
    }
}

Dialog box procedure sets and/or retrieves target image width and height value from the dialog. 

INT_PTR MainDlgProc(HWND hDlg, UINT iMessage, WPARAM wParam, LPARAM lParam)
{
    switch (iMessage) {
    case WM_INITDIALOG:
        hDlgMain = hDlg;
        SetDlgItemInt(hDlg, IDC_WIDTH, width, FALSE);
        SetDlgItemInt(hDlg, IDC_HEIGHT, height, FALSE);
 
        return TRUE;
 
    case WM_COMMAND:
        switch (LOWORD(wParam)) {
        case IDOK:
            width = GetDlgItemInt(hDlg, IDC_WIDTH, NULL, FALSE);
            height = GetDlgItemInt(hDlg, IDC_HEIGHT, NULL, FALSE);
 
            return TRUE;
 
        case IDCLOSE:
            EndDialog(hDlg, IDOK);
 
            return TRUE;
        }
    }
 
    return FALSE;
}

Run the program and select an image file.

You can change the target image size or just leave it.

Source image window.

Choose four corners from the left-top to clockwise.

Perspective transform processed image.