layout.h

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#pragma once
#include "ga/math.h"
 
namespace ga {
enum class HorzAlign
{
    LEFT,
    CENTER,
    RIGHT
};
enum class VertAlign
{
    TOP,
    MIDDLE,
    BOTTOM
};
 
// helper for alignment, returns anchor in percent
inline vec2 anchor( HorzAlign h, VertAlign v )
{
    ga::vec2 p { 0, 0 };
    switch ( h ) {
        case HorzAlign::CENTER:
            p.x = .5;
            break;
        case HorzAlign::RIGHT:
            p.x = 1.;
            break;
    }
    switch ( v ) {
        case VertAlign::MIDDLE:
            p.y = .5;
            break;
        case VertAlign::BOTTOM:
            p.y = 1.;
            break;
    }
    return p;
}
 
/*
 FitMode - describes how to scale an object to fit a container object
 */
enum class FitMode
{
    NONE,       // no auto scaling
    FIT,        // scale proportionally to fit entirely within container
    STRETCH,    // match width and height to container
    COVER,      // scale to cover container
    FIT_WIDTH,  // fit width, scale height accordingly
    FIT_HEIGHT,
    FIT_DEPTH  // for 3D
};
 
inline vec3 calcScaleToFit( const vec3& sourceSize, const vec3& containerSize, const FitMode& fitMode )
{
    vec3 scale = vec3( 1.f );
 
    // calculate sizing based on fit mode
    switch ( fitMode ) {
 
        case FitMode::FIT: {
            vec3 s   = containerSize / sourceSize;
            float s0 = std::min( std::min( s.x, s.y ), s.z );
            scale    = vec3( s0 );
            break;
        }
 
        case FitMode::STRETCH: {
            scale = containerSize / sourceSize;
            break;
        }
 
        case FitMode::COVER: {
            vec3 s   = containerSize / sourceSize;
            float s1 = std::max( std::max( s.x, s.y ), s.z );
            scale    = vec3( s1 );
            break;
        }
 
        case FitMode::FIT_WIDTH: {
            float sx = containerSize.x / sourceSize.x;
            scale    = vec3( sx );
            break;
        }
 
        case FitMode::FIT_HEIGHT: {
            float sy = containerSize.y / sourceSize.y;
            scale    = vec3( sy );
            break;
        }
 
        case FitMode::FIT_DEPTH: {
            float sz = containerSize.z / sourceSize.z;
            scale    = vec3( sz );
            break;
        }
 
        case FitMode::NONE:
        default:
            break;
    }
 
    return scale;
}
 
inline vec2 calcScaleToFit( const vec2& sourceSize, const vec2& containerSize, const FitMode& fitMode )
{
    vec2 scale = vec2( 1.f );
 
    // calculate sizing based on fit mode
    switch ( fitMode ) {
 
        case FitMode::FIT: {
            vec2 s   = containerSize / sourceSize;
            float s0 = std::min( s.x, s.y );
            scale    = vec2( s0 );
            break;
        }
 
        case FitMode::STRETCH: {
            scale = containerSize / sourceSize;
            break;
        }
 
        case FitMode::COVER: {
            vec2 s   = containerSize / sourceSize;
            float s1 = std::max( s.x, s.y );
            scale    = vec2( s1 );
            break;
        }
 
        case FitMode::FIT_WIDTH: {
            float sx = containerSize.x / sourceSize.x;
            scale    = vec2( sx );
            break;
        }
 
        case FitMode::FIT_HEIGHT: {
            float sy = containerSize.y / sourceSize.y;
            scale    = vec2( sy );
            break;
        }
 
        case FitMode::FIT_DEPTH:
        case FitMode::NONE:
        default:
            break;
    }
 
    return scale;
}
 
}  // namespace ga