ScrollView.c

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/*
 * ObjectivelyMVC: Object oriented MVC framework for SDL3 and C.
 * Copyright (C) 2014 Jay Dolan <jay@jaydolan.com>
 *
 * This software is provided 'as-is', without any express or implied
 * warranty. In no event will the authors be held liable for any damages
 * arising from the use of this software.
 *
 * Permission is granted to anyone to use this software for any purpose,
 * including commercial applications, and to alter it and redistribute it
 * freely, subject to the following restrictions:
 *
 * 1. The origin of this software must not be misrepresented; you must not
 * claim that you wrote the original software. If you use this software
 * in a product, an acknowledgment in the product documentation would be
 * appreciated but is not required.
 *
 * 2. Altered source versions must be plainly marked as such, and must not be
 * misrepresented as being the original software.
 *
 * 3. This notice may not be removed or altered from any source distribution.
 */
 
#include <assert.h>
 
#include "ScrollView.h"
 
#define _Class _ScrollView
 
#pragma mark - Object
 
static void dealloc(Object *self) {
 
  ScrollView *this = (ScrollView *) self;
 
  release(this->contentView);
 
  super(Object, self, dealloc);
}
 
#pragma mark - View
 
static void layoutSubviews(View *self) {
 
  super(View, self, layoutSubviews);
 
  ScrollView *this = (ScrollView *) self;
 
  if (this->contentView) {
    this->contentView->frame.x = this->contentOffset.x;
    this->contentView->frame.y = this->contentOffset.y;
  }
}
 
#pragma mark - Control
 
static bool captureEvent(Control *self, const SDL_Event *event) {
 
  ScrollView *this = (ScrollView *) self;
 
  if (event->type == SDL_EVENT_MOUSE_MOTION && (event->motion.state & SDL_BUTTON_LMASK)) {
    self->state |= ControlStateHighlighted;
 
    SDL_Point offset = this->contentOffset;
 
    offset.x += event->motion.xrel;
    offset.y += event->motion.yrel;
 
    $(this, scrollToOffset, &offset);
    return true;
  } else if (event->type == SDL_EVENT_MOUSE_WHEEL) {
    SDL_Point offset = this->contentOffset;
 
    offset.x -= event->wheel.x * this->step;
    offset.y += event->wheel.y * this->step;
 
    $(this, scrollToOffset, &offset);
    return true;
  } else if (event->type == SDL_EVENT_MOUSE_BUTTON_UP && (event->button.button & SDL_BUTTON_LMASK)) {
 
    if ($(self, isHighlighted)) {
      self->state &= ~ControlStateHighlighted;
      return true;
    }
  }
 
  return super(Control, self, captureEvent, event);
}
 
#pragma mark - ScrollView
 
static ScrollView *initWithFrame(ScrollView *self, const SDL_Rect *frame) {
 
  self = (ScrollView *) super(Control, self, initWithFrame, frame);
  if (self) {
    self->step = DEFAULT_SCROLL_VIEW_STEP;
  }
 
  return self;
}
 
static void scrollToOffset(ScrollView *self, const SDL_Point *offset) {
 
  if (self->contentView) {
    const SDL_Size contentSize = $(self->contentView, size);
    const SDL_Rect bounds = $((View *) self, bounds);
 
    if (contentSize.w > bounds.w) {
      self->contentOffset.x = clamp(offset->x, -(contentSize.w - bounds.w), 0);
    } else {
      self->contentOffset.x = 0;
    }
 
    if (contentSize.h > bounds.h) {
      self->contentOffset.y = clamp(offset->y, -(contentSize.h - bounds.h), 0);
    } else {
      self->contentOffset.y = 0;
    }
 
  } else {
    self->contentOffset.x = self->contentOffset.y = 0;
  }
 
  self->control.view.needsLayout = true;
}
 
static void setContentView(ScrollView *self, View *contentView) {
 
  if (contentView != self->contentView) {
 
    if (self->contentView) {
      $(self->contentView, removeClassName, "contentView");
      $((View *) self, removeSubview, self->contentView);
      self->contentView = release(self->contentView);
    }
 
    if (contentView) {
      $(contentView, addClassName, "contentView");
      $((View *) self, addSubview, contentView);
      self->contentView = retain(contentView);
    }
 
    $(self, scrollToOffset, &MakePoint(0, 0));
  }
}
 
#pragma mark - Class lifecycle
 
static void initialize(Class *clazz) {
 
  ((ObjectInterface *) clazz->interface)->dealloc = dealloc;
 
  ((ViewInterface *) clazz->interface)->layoutSubviews = layoutSubviews;
 
  ((ControlInterface *) clazz->interface)->captureEvent = captureEvent;
 
  ((ScrollViewInterface *) clazz->interface)->initWithFrame = initWithFrame;
  ((ScrollViewInterface *) clazz->interface)->scrollToOffset = scrollToOffset;
  ((ScrollViewInterface *) clazz->interface)->setContentView = setContentView;
}
 
Class *_ScrollView(void) {
  static Class *clazz;
  static Once once;
 
  do_once(&once, {
    clazz = _initialize(&(const ClassDef) {
      .name = "ScrollView",
      .superclass = _Control(),
      .instanceSize = sizeof(ScrollView),
      .interfaceOffset = offsetof(ScrollView, interface),
      .interfaceSize = sizeof(ScrollViewInterface),
      .initialize = initialize,
    });
  });
 
  return clazz;
}
 
#undef _Class