obs-studio/obs/window-basic-preview.cpp

#include <QGuiApplication>
#include <QMouseEvent>

#include <cmath>
#include <graphics/vec4.h>
#include <graphics/matrix4.h>
#include "window-basic-preview.hpp"
#include "window-basic-main.hpp"
#include "obs-app.hpp"

#define HANDLE_RADIUS     4.0f
#define HANDLE_SEL_RADIUS (HANDLE_RADIUS * 1.5f)
#define CLAMP_DISTANCE    10.0f

/* TODO: make C++ math classes and clean up code here later */

OBSBasicPreview::OBSBasicPreview(QWidget *parent, Qt::WindowFlags flags)
	: OBSQTDisplay(parent, flags)
{
	setMouseTracking(true);
}

vec2 OBSBasicPreview::GetMouseEventPos(QMouseEvent *event)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());
	vec2 pos = {
		(float(event->x()) - main->previewX) / main->previewScale,
		(float(event->y()) - main->previewY) / main->previewScale
	};

	return pos;
}

struct SceneFindData {
	const vec2   &pos;
	OBSSceneItem item;
	bool         selectBelow;

	inline SceneFindData(const vec2 &pos_, bool selectBelow_)
		: pos         (pos_),
		  selectBelow (selectBelow_)
	{}
};

static bool FindItemAtPos(obs_scene_t scene, obs_sceneitem_t item, void *param)
{
	SceneFindData *data = reinterpret_cast<SceneFindData*>(param);
	matrix4       transform;
	vec3          transformedPos;
	vec3          pos3 = {data->pos.x, data->pos.y, 0.0f};

	obs_sceneitem_get_box_transform(item, &transform);

	matrix4_inv(&transform, &transform);
	vec3_transform(&transformedPos, &pos3, &transform);

	if (transformedPos.x >= 0.0f && transformedPos.x <= 1.0f &&
	    transformedPos.y >= 0.0f && transformedPos.y <= 1.0f) {
		if (data->selectBelow && obs_sceneitem_selected(item)) {
			if (data->item)
				return false;
			else
				data->selectBelow = false;
		}

		data->item = item;
	}

	UNUSED_PARAMETER(scene);
	return true;
}

static vec3 GetTransformedPos(float x, float y, const matrix4 &mat)
{
	vec3 result;
	vec3_set(&result, x, y, 0.0f);
	vec3_transform(&result, &result, &mat);
	return result;
}

static vec3 GetTransformedPosScaled(float x, float y, const matrix4 &mat,
		float scale)
{
	vec3 result;
	vec3_set(&result, x, y, 0.0f);
	vec3_transform(&result, &result, &mat);
	vec3_mulf(&result, &result, scale);
	return result;
}

static inline vec2 GetOBSScreenSize()
{
	obs_video_info ovi;
	vec2 size = {0.0f, 0.0f};

	if (obs_get_video_info(&ovi)) {
		size.x = float(ovi.base_width);
		size.y = float(ovi.base_height);
	}

	return size;
}

vec3 OBSBasicPreview::GetScreenSnapOffset(const vec3 &tl, const vec3 &br)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());
	vec2 screenSize = GetOBSScreenSize();
	vec3 clampOffset;

	vec3_zero(&clampOffset);

	const float clampDist = CLAMP_DISTANCE / main->previewScale;

	if (fabsf(tl.x) < clampDist)
		clampOffset.x = -tl.x;
	if (fabsf(clampOffset.x) < EPSILON &&
	    fabsf(screenSize.x - br.x) < clampDist)
		clampOffset.x = screenSize.x - br.x;

	if (fabsf(tl.y) < clampDist)
		clampOffset.y = -tl.y;
	if (fabsf(clampOffset.y) < EPSILON &&
	    fabsf(screenSize.y - br.y) < clampDist)
		clampOffset.y = screenSize.y - br.y;

	return clampOffset;
}

OBSSceneItem OBSBasicPreview::GetItemAtPos(const vec2 &pos, bool selectBelow)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());

	OBSScene scene = main->GetCurrentScene();
	if (!scene)
		return OBSSceneItem();

	SceneFindData data(pos, selectBelow);
	obs_scene_enum_items(scene, FindItemAtPos, &data);
	return data.item;
}

static bool CheckItemSelected(obs_scene_t scene, obs_sceneitem_t item,
		void *param)
{
	SceneFindData *data = reinterpret_cast<SceneFindData*>(param);
	matrix4       transform;
	vec3          transformedPos;
	vec3          pos3 = {data->pos.x, data->pos.y, 0.0f};

	obs_sceneitem_get_box_transform(item, &transform);

	matrix4_inv(&transform, &transform);
	vec3_transform(&transformedPos, &pos3, &transform);

	if (transformedPos.x >= 0.0f && transformedPos.x <= 1.0f &&
	    transformedPos.y >= 0.0f && transformedPos.y <= 1.0f) {
		if (obs_sceneitem_selected(item)) {
			data->item = item;
			return false;
		}
	}

	UNUSED_PARAMETER(scene);
	return true;
}

bool OBSBasicPreview::SelectedAtPos(const vec2 &pos)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());

	OBSScene scene = main->GetCurrentScene();
	if (!scene)
		return false;

	SceneFindData data(pos, false);
	obs_scene_enum_items(scene, CheckItemSelected, &data);
	return !!data.item;
}

struct HandleFindData {
	const vec2   &pos;
	const float  scale;

	OBSSceneItem item;
	ItemHandle   handle = ItemHandle::None;

	inline HandleFindData(const vec2 &pos_, float scale_)
		: pos   (pos_),
		  scale (scale_)
	{}
};

static bool FindHandleAtPos(obs_scene_t scene, obs_sceneitem_t item,
		void *param)
{
	if (!obs_sceneitem_selected(item))
		return true;

	HandleFindData *data = reinterpret_cast<HandleFindData*>(param);
	matrix4        transform;
	vec3           pos3 = {data->pos.x, data->pos.y, 0.0f};
	float          closestHandle = HANDLE_SEL_RADIUS;

	obs_sceneitem_get_box_transform(item, &transform);

	auto TestHandle = [&] (float x, float y, ItemHandle handle)
	{
		vec3 handlePos = GetTransformedPosScaled(x, y, transform,
				data->scale);

		float dist = vec3_dist(&handlePos, &pos3);
		if (dist < HANDLE_SEL_RADIUS) {
			if (dist < closestHandle) {
				closestHandle = dist;
				data->handle  = handle;
				data->item    = item;
			}
		}
	};

	TestHandle(0.0f, 0.0f, ItemHandle::TopLeft);
	TestHandle(0.5f, 0.0f, ItemHandle::TopCenter);
	TestHandle(1.0f, 0.0f, ItemHandle::TopRight);
	TestHandle(0.0f, 0.5f, ItemHandle::CenterLeft);
	TestHandle(1.0f, 0.5f, ItemHandle::CenterRight);
	TestHandle(0.0f, 1.0f, ItemHandle::BottomLeft);
	TestHandle(0.5f, 1.0f, ItemHandle::BottomCenter);
	TestHandle(1.0f, 1.0f, ItemHandle::BottomRight);

	UNUSED_PARAMETER(scene);
	return true;
}

static vec2 GetItemSize(obs_sceneitem_t item)
{
	obs_bounds_type boundsType = obs_sceneitem_get_bounds_type(item);
	vec2 size;

	if (boundsType != OBS_BOUNDS_NONE) {
		obs_sceneitem_get_bounds(item, &size);
	} else {
		obs_source_t source = obs_sceneitem_getsource(item);
		vec2 scale;

		obs_sceneitem_getscale(item, &scale);
		size.x = float(obs_source_getwidth(source))  * scale.x;
		size.y = float(obs_source_getheight(source)) * scale.y;
	}

	return size;
}

void OBSBasicPreview::GetStretchHandleData(const vec2 &pos)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());

	OBSScene scene = main->GetCurrentScene();
	if (!scene)
		return;

	HandleFindData data(pos, main->previewScale);
	obs_scene_enum_items(scene, FindHandleAtPos, &data);

	stretchItem     = std::move(data.item);
	stretchHandle   = data.handle;

	if (stretchHandle != ItemHandle::None) {
		matrix4 boxTransform;
		vec3    itemUL;
		float   itemRot;

		stretchItemSize = GetItemSize(stretchItem);

		obs_sceneitem_get_box_transform(stretchItem, &boxTransform);
		itemRot = obs_sceneitem_getrot(stretchItem);
		vec3_from_vec4(&itemUL, &boxTransform.t);

		/* build the item space conversion matrices */
		matrix4_identity(&itemToScreen);
		matrix4_rotate_aa4f(&itemToScreen, &itemToScreen,
				0.0f, 0.0f, 1.0f, RAD(itemRot));
		matrix4_translate3f(&itemToScreen, &itemToScreen,
				itemUL.x, itemUL.y, 0.0f);

		matrix4_identity(&screenToItem);
		matrix4_translate3f(&screenToItem, &screenToItem,
				-itemUL.x, -itemUL.y, 0.0f);
		matrix4_rotate_aa4f(&screenToItem, &screenToItem,
				0.0f, 0.0f, 1.0f, RAD(-itemRot));
	}
}

void OBSBasicPreview::mousePressEvent(QMouseEvent *event)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());
	float x = float(event->x()) - main->previewX;
	float y = float(event->y()) - main->previewY;

	if (event->button() != Qt::LeftButton)
		return;

	mouseDown = true;

	vec2_set(&startPos, x, y);
	GetStretchHandleData(startPos);

	vec2_divf(&startPos, &startPos, main->previewScale);
	startPos.x = std::round(startPos.x);
	startPos.y = std::round(startPos.y);

	mouseOverItems = SelectedAtPos(startPos);
	vec2_zero(&lastMoveOffset);
}

static bool select_one(obs_scene_t scene, obs_sceneitem_t item, void *param)
{
	obs_sceneitem_t selectedItem = reinterpret_cast<obs_sceneitem_t>(param);
	obs_sceneitem_select(item, (selectedItem == item));

	UNUSED_PARAMETER(scene);
	return true;
}

void OBSBasicPreview::DoSelect(const vec2 &pos)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());

	OBSScene     scene = main->GetCurrentScene();
	OBSSceneItem item  = GetItemAtPos(pos, true);

	obs_scene_enum_items(scene, select_one, (obs_sceneitem_t)item);
}

void OBSBasicPreview::DoCtrlSelect(const vec2 &pos)
{
	OBSSceneItem item = GetItemAtPos(pos, false);
	if (!item)
		return;

	bool selected = obs_sceneitem_selected(item);
	obs_sceneitem_select(item, !selected);
}

void OBSBasicPreview::ProcessClick(const vec2 &pos)
{
	Qt::KeyboardModifiers modifiers = QGuiApplication::keyboardModifiers();

	if (modifiers & Qt::ControlModifier)
		DoCtrlSelect(pos);
	else
		DoSelect(pos);
}

void OBSBasicPreview::mouseReleaseEvent(QMouseEvent *event)
{
	if (mouseDown) {
		vec2 pos = GetMouseEventPos(event);

		if (!mouseMoved)
			ProcessClick(pos);

		stretchItem = nullptr;
		mouseDown   = false;
		mouseMoved  = false;
	}
}

struct SelectedItemBounds {
	bool first = true;
	vec3 tl, br;
};

static bool AddItemBounds(obs_scene_t scene, obs_sceneitem_t item,
		void *param)
{
	SelectedItemBounds *data = reinterpret_cast<SelectedItemBounds*>(param);

	if (!obs_sceneitem_selected(item))
		return true;

	matrix4 boxTransform;
	obs_sceneitem_get_box_transform(item, &boxTransform);

	vec3 t[4] = {
		GetTransformedPos(0.0f, 0.0f, boxTransform),
		GetTransformedPos(1.0f, 0.0f, boxTransform),
		GetTransformedPos(0.0f, 1.0f, boxTransform),
		GetTransformedPos(1.0f, 1.0f, boxTransform)
	};

	for (const vec3 &v : t) {
		if (data->first) {
			vec3_copy(&data->tl, &v);
			vec3_copy(&data->br, &v);
			data->first = false;
		} else {
			vec3_min(&data->tl, &data->tl, &v);
			vec3_max(&data->br, &data->br, &v);
		}
	}

	UNUSED_PARAMETER(scene);
	return true;
}

void OBSBasicPreview::SnapItemMovement(vec2 &offset)
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());
	OBSScene scene = main->GetCurrentScene();

	SelectedItemBounds data;
	obs_scene_enum_items(scene, AddItemBounds, &data);

	data.tl.x += offset.x;
	data.tl.y += offset.y;
	data.br.x += offset.x;
	data.br.y += offset.y;

	vec3 snapOffset = GetScreenSnapOffset(data.tl, data.br);
	offset.x += snapOffset.x;
	offset.y += snapOffset.y;
}

static bool move_items(obs_scene_t scene, obs_sceneitem_t item, void *param)
{
	vec2 *offset = reinterpret_cast<vec2*>(param);

	if (obs_sceneitem_selected(item)) {
		vec2 pos;
		obs_sceneitem_getpos(item, &pos);
		vec2_add(&pos, &pos, offset);
		obs_sceneitem_setpos(item, &pos);
	}

	UNUSED_PARAMETER(scene);
	return true;
}

void OBSBasicPreview::MoveItems(const vec2 &pos)
{
	Qt::KeyboardModifiers modifiers = QGuiApplication::keyboardModifiers();
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());
	OBSScene scene = main->GetCurrentScene();

	vec2 offset, moveOffset;
	vec2_sub(&offset, &pos, &startPos);
	vec2_sub(&moveOffset, &offset, &lastMoveOffset);

	if (!(modifiers & Qt::ControlModifier))
		SnapItemMovement(moveOffset);

	vec2_add(&lastMoveOffset, &lastMoveOffset, &moveOffset);

	obs_scene_enum_items(scene, move_items, &moveOffset);
}

vec3 OBSBasicPreview::CalculateStretchPos(const vec3 &tl, const vec3 &br)
{
	uint32_t alignment = obs_sceneitem_getalignment(stretchItem);
	vec3 pos;

	vec3_zero(&pos);

	if (alignment & OBS_ALIGN_LEFT)
		pos.x = tl.x;
	else if (alignment & OBS_ALIGN_RIGHT)
		pos.x = br.x;
	else
		pos.x = (br.x - tl.x) * 0.5f + tl.x;

	if (alignment & OBS_ALIGN_TOP)
		pos.y = tl.y;
	else if (alignment & OBS_ALIGN_BOTTOM)
		pos.y = br.y;
	else
		pos.y = (br.y - tl.y) * 0.5f + tl.y;

	return pos;
}

void OBSBasicPreview::ClampAspect(vec3 &tl, vec3 &br, vec2 &size,
		const vec2 &baseSize)
{
	float    baseAspect   = baseSize.x / baseSize.y;
	float    aspect       = size.x / size.y;
	uint32_t stretchFlags = (uint32_t)stretchHandle;

	if (stretchHandle == ItemHandle::TopLeft    ||
	    stretchHandle == ItemHandle::TopRight   ||
	    stretchHandle == ItemHandle::BottomLeft ||
	    stretchHandle == ItemHandle::BottomRight) {
		if (aspect < baseAspect)
			size.x = size.y * baseAspect;
		else
			size.y = size.x / baseAspect;

	} else if (stretchHandle == ItemHandle::TopCenter ||
	           stretchHandle == ItemHandle::BottomCenter) {
		size.x = size.y * baseAspect;

	} else if (stretchHandle == ItemHandle::CenterLeft ||
	           stretchHandle == ItemHandle::CenterRight) {
		size.y = size.x / baseAspect;
	}

	size.x = std::round(size.x);
	size.y = std::round(size.y);

	if (stretchFlags & ITEM_LEFT)
		tl.x = br.x - size.x;
	else if (stretchFlags & ITEM_RIGHT)
		br.x = tl.x + size.x;

	if (stretchFlags & ITEM_TOP)
		tl.y = br.y - size.y;
	else if (stretchFlags & ITEM_BOTTOM)
		br.y = tl.y + size.y;
}

void OBSBasicPreview::SnapStretchingToScreen(vec3 &tl, vec3 &br)
{
	uint32_t stretchFlags = (uint32_t)stretchHandle;
	vec3     newTL        = GetTransformedPos(tl.x, tl.y, itemToScreen);
	vec3     newTR        = GetTransformedPos(br.x, tl.y, itemToScreen);
	vec3     newBL        = GetTransformedPos(tl.x, br.y, itemToScreen);
	vec3     newBR        = GetTransformedPos(br.x, br.y, itemToScreen);
	vec3     boundingTL;
	vec3     boundingBR;

	vec3_copy(&boundingTL, &newTL);
	vec3_min(&boundingTL, &boundingTL, &newTR);
	vec3_min(&boundingTL, &boundingTL, &newBL);
	vec3_min(&boundingTL, &boundingTL, &newBR);

	vec3_copy(&boundingBR, &newTL);
	vec3_max(&boundingBR, &boundingBR, &newTR);
	vec3_max(&boundingBR, &boundingBR, &newBL);
	vec3_max(&boundingBR, &boundingBR, &newBR);

	vec3 offset = GetScreenSnapOffset(boundingTL, boundingBR);
	vec3_add(&offset, &offset, &newTL);
	vec3_transform(&offset, &offset, &screenToItem);
	vec3_sub(&offset, &offset, &tl);

	if (stretchFlags & ITEM_LEFT)
		tl.x += offset.x;
	else if (stretchFlags & ITEM_RIGHT)
		br.x += offset.x;

	if (stretchFlags & ITEM_TOP)
		tl.y += offset.y;
	else if (stretchFlags & ITEM_BOTTOM)
		br.y += offset.y;
}

void OBSBasicPreview::StretchItem(const vec2 &pos)
{
	Qt::KeyboardModifiers modifiers = QGuiApplication::keyboardModifiers();
	obs_bounds_type boundsType = obs_sceneitem_get_bounds_type(stretchItem);
	uint32_t stretchFlags = (uint32_t)stretchHandle;
	bool shiftDown = (modifiers & Qt::ShiftModifier);
	vec3 tl, br, pos3;

	vec3_zero(&tl);
	vec3_set(&br, stretchItemSize.x, stretchItemSize.y, 0.0f);

	vec3_set(&pos3, pos.x, pos.y, 0.0f);
	vec3_transform(&pos3, &pos3, &screenToItem);

	if (stretchFlags & ITEM_LEFT)
		tl.x = pos3.x;
	else if (stretchFlags & ITEM_RIGHT)
		br.x = pos3.x;

	if (stretchFlags & ITEM_TOP)
		tl.y = pos3.y;
	else if (stretchFlags & ITEM_BOTTOM)
		br.y = pos3.y;

	if (!(modifiers & Qt::ControlModifier))
		SnapStretchingToScreen(tl, br);

	obs_source_t source = obs_sceneitem_getsource(stretchItem);
	vec2 baseSize = {
		float(obs_source_getwidth(source)),
		float(obs_source_getheight(source))
	};

	vec2 size = {br.x - tl.x, br.y - tl.y};

	if (boundsType != OBS_BOUNDS_NONE) {
		if (boundsType == OBS_BOUNDS_STRETCH && !shiftDown)
			ClampAspect(tl, br, size, baseSize);

		if (tl.x > br.x) std::swap(tl.x, br.x);
		if (tl.y > br.y) std::swap(tl.y, br.y);

		vec2_abs(&size, &size);

		obs_sceneitem_set_bounds(stretchItem, &size);
	} else {
		if (!shiftDown)
			ClampAspect(tl, br, size, baseSize);

		vec2_div(&size, &size, &baseSize);
		obs_sceneitem_setscale(stretchItem, &size);
	}

	pos3 = CalculateStretchPos(tl, br);
	vec3_transform(&pos3, &pos3, &itemToScreen);
	vec2 newPos = {pos3.x, pos3.y};

	newPos.x = std::round(newPos.x);
	newPos.y = std::round(newPos.y);

	obs_sceneitem_setpos(stretchItem, &newPos);
}

void OBSBasicPreview::mouseMoveEvent(QMouseEvent *event)
{
	if (mouseDown) {
		vec2 pos = GetMouseEventPos(event);

		if (!mouseMoved && !mouseOverItems &&
		    stretchHandle == ItemHandle::None) {
			ProcessClick(startPos);
			mouseOverItems = SelectedAtPos(startPos);
		}

		pos.x = std::round(pos.x);
		pos.y = std::round(pos.y);

		if (stretchHandle != ItemHandle::None)
			StretchItem(pos);
		else if (mouseOverItems)
			MoveItems(pos);

		mouseMoved = true;
	}
}

static void DrawCircleAtPos(float x, float y, matrix4 &matrix,
		float previewScale)
{
	struct vec3 pos;
	vec3_set(&pos, x, y, 0.0f);
	vec3_transform(&pos, &pos, &matrix);
	vec3_mulf(&pos, &pos, previewScale);

	gs_matrix_push();
	gs_matrix_translate(&pos);
	gs_draw(GS_LINESTRIP, 0, 0);
	gs_matrix_pop();
}

bool OBSBasicPreview::DrawSelectedItem(obs_scene_t scene, obs_sceneitem_t item,
		void *param)
{
	if (!obs_sceneitem_selected(item))
		return true;

	OBSBasicPreview *preview = reinterpret_cast<OBSBasicPreview*>(param);
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());

	gs_load_vertexbuffer(main->circle);

	matrix4 boxTransform;
	obs_sceneitem_get_box_transform(item, &boxTransform);

	gs_matrix_push();
	gs_matrix_scale3f(HANDLE_RADIUS, HANDLE_RADIUS, 1.0f);
	DrawCircleAtPos(0.0f, 0.0f, boxTransform, main->previewScale);
	DrawCircleAtPos(0.0f, 1.0f, boxTransform, main->previewScale);
	DrawCircleAtPos(1.0f, 0.0f, boxTransform, main->previewScale);
	DrawCircleAtPos(1.0f, 1.0f, boxTransform, main->previewScale);
	DrawCircleAtPos(0.5f, 0.0f, boxTransform, main->previewScale);
	DrawCircleAtPos(0.0f, 0.5f, boxTransform, main->previewScale);
	DrawCircleAtPos(0.5f, 1.0f, boxTransform, main->previewScale);
	DrawCircleAtPos(1.0f, 0.5f, boxTransform, main->previewScale);
	gs_matrix_pop();

	gs_load_vertexbuffer(main->box);

	gs_matrix_push();
	gs_matrix_set(&boxTransform);
	gs_matrix_scale3f(main->previewScale, main->previewScale, 1.0f);
	gs_draw(GS_LINESTRIP, 0, 0);

	gs_matrix_pop();

	UNUSED_PARAMETER(scene);
	return true;
}

void OBSBasicPreview::DrawSceneEditing()
{
	OBSBasic *main = reinterpret_cast<OBSBasic*>(App()->GetMainWindow());

	effect_t    solid = obs_get_solid_effect();
	technique_t tech  = effect_gettechnique(solid, "Solid");

	vec4 color;
	vec4_set(&color, 1.0f, 0.0f, 0.0f, 1.0f);
	effect_setvec4(solid, effect_getparambyname(solid, "color"), &color);

	technique_begin(tech);
	technique_beginpass(tech, 0);

	OBSScene scene = main->GetCurrentScene();
	if (scene)
		obs_scene_enum_items(scene, DrawSelectedItem, this);

	gs_load_vertexbuffer(nullptr);

	technique_endpass(tech);
	technique_end(tech);
}