FMXTBitmapStartLine (C++)

Description

This example shows how to use the TBitmap.StartLine property. This example rotates the RGB channel color of every pixel of an image.

To build and test this example, create a FireMonkey HD Application - C++, then add the next objects to the form:

• A TImage to display the initial TBitmap.
• A TImage to display the result.
• Two TLabel, one for each TImage.
• A TButton to draw on the initial image.
• A TOpenDialog and a TButton to load the image to be customized.

Add the following code to the OnClick event handlers of the load button.

Code

void __fastcall TForm1::Button2Click(TObject *Sender) {
        if (OpenDialog1->Execute()) {
                Image1->Bitmap->LoadFromFile(OpenDialog1->FileName);
        }
}

Add the following code to the OnClick event handlers of the other button.

Code

void __fastcall TForm1::Button1Click(TObject *Sender) {
        TBitmap *MyBitmap = new TBitmap(0, 0);
        int I;
        Byte T;
        PAlphaColorRecArray PixelRecs;
        try {
                if (Image1->Bitmap->IsEmpty()) {
                        // Display a message when there is no image loaded
                        MessageDlg("There is no image to customize:",
                                TMsgDlgType::mtWarning,
                        TMsgDlgButtons() << TMsgDlgBtn::mbOK, 0);
                }
                else {
                        // A copy of the initial bitmap
                        MyBitmap->Assign(Image1->Bitmap);
                        // Cast from 32-bit colors to color record
                        PixelRecs = PAlphaColorRecArray(MyBitmap->StartLine);
                        // Rotate RGB of every pixel
                        for (I = 0; I < MyBitmap->Width * MyBitmap->Height - 1; I++) {
                                T = (*PixelRecs)[I].R; // temp
                                (*PixelRecs)[I].R = (*PixelRecs)[I].G;
                                (*PixelRecs)[I].G = (*PixelRecs)[I].B;
                                (*PixelRecs)[I].B = T;
                        }
 
                        // Display the result
                        Image2->Bitmap = MyBitmap;
 
                }
        }
        __finally {
                delete MyBitmap;
        }
}

The result should look like in the following image:

Uses

• FMX.Types.TBitmap.StartLine ( fr | de | ja )

• FMX.Types.PAlphaColorRecArray ( fr | de | ja )

• FMX.Objects.TImage.Bitmap ( fr | de | ja )

See Also

• FMX.Objects.Objects.TImage ( fr | de | ja )
• FMX.Dialogs.TOpenDialog( fr | de | ja )
• Delphi version of this example