Drawing image dynamically?

General JUCE discussion
4

If you have a complex background you want for your Component and you don’t need it to be redrawn from scratch in your paint() method you can create a background Image and use that in your paint() method.

Something like:

void CMidiDisplayComponent::createNewBackground()
{
   m_GrooveBackground = Image (Image::RGB,
                           jmax (1, m_Background.getWidth()), jmax (1, m_Background.getHeight()),
                           true);

    Graphics g (m_GrooveBackground);    // m_GrooveBackground is a class Image member

    g.drawImageAt (m_Background, 0, 0);  // m_Background is a class Image member

    drawStaffLines (g);

    :

    repaint();
}

then

 void CMidiDisplayComponent::paint (Graphics& g)
{
    g.drawImageAt (m_GrooveBackground, 0, 0);
}

That way the background in this example only gets recalculated/redrawn when the groove’s length changes.

Rail

2 Likes