Custom Alignment Scaling Mode

Yes, it's definitely possible to implement a ScalingMode that maintains aspect ratio while aligning the image to a specific corner or edge. This is a great feature to add more flexibility to our Image class. Let's call this new mode AlignedContain.

To implement this, we'll need to make several modifications to our Image class. First, let's define an Alignment enum to specify the desired alignment:

1enum class Alignment {
2  TopLeft, TopCenter, TopRight,
3  CenterLeft, Center, CenterRight,
4  BottomLeft, BottomCenter, BottomRight
5};

We'll need to add a new member variable to store the alignment:

1class Image {
2private:
3  // ... other members ...
4  Alignment mAlignment{Alignment::Center};
5  // ... other members ...
6};

Now, let's modify our MatchAspectRatio() function to handle the alignment:

1SDL_Rect Image::MatchAspectRatio(
2  const SDL_Rect& Source,
3  const SDL_Rect& Target) const {
4  float TargetRatio{ Target.w
5    / static_cast<float>(Target.h) };
6  float SourceRatio{ Source.w
7    / static_cast<float>(Source.h) };
8
9  SDL_Rect ReturnValue = Source;
10
11  if (SourceRatio < TargetRatio) {
12    ReturnValue.h =
13      static_cast<int>(Source.w / TargetRatio);
14  } else {
15    ReturnValue.w =
16      static_cast<int>(Source.h * TargetRatio);
17  }
18
19  switch (mAlignment) {
20    case Alignment::TopLeft:
21      ReturnValue.x = Source.x;
22      ReturnValue.y = Source.y;
23      break;
24    case Alignment::TopCenter:
25      ReturnValue.x = Source.x
26        + (Source.w - ReturnValue.w) / 2;
27      ReturnValue.y = Source.y;
28      break;
29    // ... (other alignment cases)
30  }
31
32  return ReturnValue;
33}

Add a method to set the alignment:

1void Image::SetAlignment(Alignment Align) {
2  mAlignment = Align;
3  SetDestinationRectangle(mRequestedDestRectangle);
4}

With these changes, we can now use the SetAlignment() method to maintain aspect ratio while aligning the image to a specific corner or edge. Here's an example of how to use it:

1Image MyImage{
2  "example.png",
3  SrcRect, DestRect,
4  ScalingMode::Contain
5};
6MyImage.SetAlignment(Alignment::TopLeft);

This implementation gives users fine-grained control over image positioning while still maintaining aspect ratio, making it easier to create complex layouts in games or other graphical applications.