summaryrefslogtreecommitdiffstats
path: root/gui/scrolllist.cpp
blob: ecfb5fe81f7042c266a22b3b0e82071def4b8b40 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
/*
	Copyright 2013 bigbiff/Dees_Troy TeamWin
	This file is part of TWRP/TeamWin Recovery Project.

	TWRP is free software: you can redistribute it and/or modify
	it under the terms of the GNU General Public License as published by
	the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.

	TWRP is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	You should have received a copy of the GNU General Public License
	along with TWRP.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <string.h>

extern "C" {
#include "../twcommon.h"
}
#include "../minuitwrp/minui.h"

#include "rapidxml.hpp"
#include "objects.hpp"
#include "../data.hpp"

const float SCROLLING_SPEED_DECREMENT = 0.9; // friction
const int SCROLLING_FLOOR = 2; // minimum pixels for scrolling to stop

GUIScrollList::GUIScrollList(xml_node<>* node) : GUIObject(node)
{
	xml_node<>* child;

	firstDisplayedItem = mItemSpacing = mFontHeight = mSeparatorH = y_offset = scrollingSpeed = 0;
	maxIconWidth = maxIconHeight =  mHeaderIconHeight = mHeaderIconWidth = 0;
	mHeaderSeparatorH = mHeaderH = actualItemHeight = 0;
	mHeaderIsStatic = false;
	mBackground = mHeaderIcon = NULL;
	mFont = NULL;
	mFastScrollW = mFastScrollLineW = mFastScrollRectW = mFastScrollRectH = 0;
	mFastScrollRectCurrentY = mFastScrollRectCurrentH = mFastScrollRectTouchY = 0;
	lastY = last2Y = fastScroll = 0;
	mUpdate = 0;
	touchDebounce = 6;
	ConvertStrToColor("black", &mBackgroundColor);
	ConvertStrToColor("black", &mHeaderBackgroundColor);
	ConvertStrToColor("black", &mSeparatorColor);
	ConvertStrToColor("black", &mHeaderSeparatorColor);
	ConvertStrToColor("white", &mFontColor);
	ConvertStrToColor("white", &mHeaderFontColor);
	ConvertStrToColor("white", &mFastScrollLineColor);
	ConvertStrToColor("white", &mFastScrollRectColor);
	hasHighlightColor = false;
	allowSelection = true;
	selectedItem = NO_ITEM;

	// Load header text
	// note: node can be NULL for the emergency console
	child = node ? node->first_node("text") : NULL;
	if (child)  mHeaderText = child->value();
	// Simple way to check for static state
	mLastHeaderValue = gui_parse_text(mHeaderText);
	mHeaderIsStatic = (mLastHeaderValue == mHeaderText);

	mHighlightColor = LoadAttrColor(FindNode(node, "highlight"), "color", &hasHighlightColor);

	child = FindNode(node, "background");
	if (child)
	{
		mBackground = LoadAttrImage(child, "resource");
		mBackgroundColor = LoadAttrColor(child, "color");
	}

	// Load the placement
	LoadPlacement(FindNode(node, "placement"), &mRenderX, &mRenderY, &mRenderW, &mRenderH);
	SetActionPos(mRenderX, mRenderY, mRenderW, mRenderH);

	// Load the font, and possibly override the color
	child = FindNode(node, "font");
	if (child)
	{
		mFont = LoadAttrFont(child, "resource");
		mFontColor = LoadAttrColor(child, "color");
		mFontHighlightColor = LoadAttrColor(child, "highlightcolor", mFontColor);
		mItemSpacing = LoadAttrIntScaleY(child, "spacing");
	}

	// Load the separator if it exists
	child = FindNode(node, "separator");
	if (child)
	{
		mSeparatorColor = LoadAttrColor(child, "color");
		mSeparatorH = LoadAttrIntScaleY(child, "height");
	}

	// Fast scroll
	child = FindNode(node, "fastscroll");
	if (child)
	{
		mFastScrollLineColor = LoadAttrColor(child, "linecolor");
		mFastScrollRectColor = LoadAttrColor(child, "rectcolor");

		mFastScrollW = LoadAttrIntScaleX(child, "w");
		mFastScrollLineW = LoadAttrIntScaleX(child, "linew");
		mFastScrollRectW = LoadAttrIntScaleX(child, "rectw");
		mFastScrollRectH = LoadAttrIntScaleY(child, "recth");
	}

	// Retrieve the line height
	mFontHeight = mFont->GetHeight();
	actualItemHeight = mFontHeight + mItemSpacing + mSeparatorH;

	// Load the header if it exists
	child = FindNode(node, "header");
	if (child)
	{
		mHeaderH = mFontHeight;
		mHeaderIcon = LoadAttrImage(child, "icon");
		mHeaderBackgroundColor = LoadAttrColor(child, "background", mBackgroundColor);
		mHeaderFontColor = LoadAttrColor(child, "textcolor", mFontColor);
		mHeaderSeparatorColor = LoadAttrColor(child, "separatorcolor", mSeparatorColor);
		mHeaderSeparatorH = LoadAttrIntScaleY(child, "separatorheight", mSeparatorH);

		if (mHeaderIcon && mHeaderIcon->GetResource())
		{
			mHeaderIconWidth = mHeaderIcon->GetWidth();
			mHeaderIconHeight = mHeaderIcon->GetHeight();
			if (mHeaderIconHeight > mHeaderH)
				mHeaderH = mHeaderIconHeight;
			if (mHeaderIconWidth > maxIconWidth)
				maxIconWidth = mHeaderIconWidth;
		}

		mHeaderH += mItemSpacing + mHeaderSeparatorH;
		if (mHeaderH < actualItemHeight)
			mHeaderH = actualItemHeight;
	}

	if (actualItemHeight / 3 > 6)
		touchDebounce = actualItemHeight / 3;
}

GUIScrollList::~GUIScrollList()
{
}

void GUIScrollList::SetMaxIconSize(int w, int h)
{
	if (w > maxIconWidth)
		maxIconWidth = w;
	if (h > maxIconHeight)
		maxIconHeight = h;
	if (maxIconHeight > mFontHeight) {
		actualItemHeight = maxIconHeight + mItemSpacing + mSeparatorH;
		if (mHeaderH > 0 && actualItemHeight > mHeaderH)
			mHeaderH = actualItemHeight;
	}
}

void GUIScrollList::SetVisibleListLocation(size_t list_index)
{
	// This will make sure that the item indicated by list_index is visible on the screen
	size_t lines = GetDisplayItemCount();

	if (list_index <= (unsigned)firstDisplayedItem) {
		// list_index is above the currently displayed items, put the selected item at the very top
		firstDisplayedItem = list_index;
		y_offset = 0;
	} else if (list_index >= firstDisplayedItem + lines) {
		// list_index is below the currently displayed items, put the selected item at the very bottom
		firstDisplayedItem = list_index - lines + 1;
		if (GetDisplayRemainder() != 0) {
			// There's a partial row displayed, set the scrolling offset so that the selected item really is at the very bottom
			firstDisplayedItem--;
			y_offset = GetDisplayRemainder() - actualItemHeight;
		} else {
			// There's no partial row so zero out the offset
			y_offset = 0;
		}
		if (firstDisplayedItem < 0)
			firstDisplayedItem = 0;
	}
	scrollingSpeed = 0; // stop kinetic scrolling on setting visible location
	mUpdate = 1;
}

int GUIScrollList::Render(void)
{
	if (!isConditionTrue())
		return 0;

	// First step, fill background
	gr_color(mBackgroundColor.red, mBackgroundColor.green, mBackgroundColor.blue, mBackgroundColor.alpha);
	gr_fill(mRenderX, mRenderY + mHeaderH, mRenderW, mRenderH - mHeaderH);

	// don't paint outside of the box
	gr_clip(mRenderX, mRenderY, mRenderW, mRenderH);

	// Next, render the background resource (if it exists)
	if (mBackground && mBackground->GetResource())
	{
		int BackgroundW = mBackground->GetWidth();
		int BackgroundH = mBackground->GetHeight();
		int BackgroundX = mRenderX + ((mRenderW - BackgroundW) / 2);
		int BackgroundY = mRenderY + ((mRenderH - BackgroundH) / 2);
		gr_blit(mBackground->GetResource(), 0, 0, BackgroundW, BackgroundH, BackgroundX, BackgroundY);
	}

	// This tells us how many full lines we can actually render
	size_t lines = GetDisplayItemCount();

	size_t listSize = GetItemCount();
	int listW = mRenderW; // this is only used for the separators - the list items are rendered in the full width of the list

	if (listSize <= lines) {
		hasScroll = false;
		scrollingSpeed = 0;
		lines = listSize;
		y_offset = 0;
	} else {
		hasScroll = true;
		listW -= mFastScrollW; // space for fast scroll
		lines++;
		if (lines < listSize)
			lines++;
	}

	int yPos = mRenderY + mHeaderH + y_offset;

	// render all visible items
	for (size_t line = 0; line < lines; line++)
	{
		size_t itemindex = line + firstDisplayedItem;
		if (itemindex >= listSize)
			break;

		RenderItem(itemindex, yPos, itemindex == selectedItem);

		// Add the separator
		gr_color(mSeparatorColor.red, mSeparatorColor.green, mSeparatorColor.blue, mSeparatorColor.alpha);
		gr_fill(mRenderX, yPos + actualItemHeight - mSeparatorH, listW, mSeparatorH);

		// Move the yPos
		yPos += actualItemHeight;
	}

	// Render the Header (last so that it overwrites the top most row for per pixel scrolling)
	yPos = mRenderY;
	if (mHeaderH > 0) {
		// First step, fill background
		gr_color(mHeaderBackgroundColor.red, mHeaderBackgroundColor.green, mHeaderBackgroundColor.blue, mHeaderBackgroundColor.alpha);
		gr_fill(mRenderX, mRenderY, mRenderW, mHeaderH);

		int IconOffsetX = 0;

		// render the icon if it exists
		if (mHeaderIcon && mHeaderIcon->GetResource())
		{
			gr_blit(mHeaderIcon->GetResource(), 0, 0, mHeaderIconWidth, mHeaderIconHeight, mRenderX + ((mHeaderIconWidth - maxIconWidth) / 2), (yPos + (int)((mHeaderH - mHeaderIconHeight) / 2)));
			IconOffsetX = maxIconWidth;
		}

		// render the text
		if (mFont && mFont->GetResource()) {
			gr_color(mHeaderFontColor.red, mHeaderFontColor.green, mHeaderFontColor.blue, mHeaderFontColor.alpha);
			gr_textEx_scaleW(mRenderX + IconOffsetX + 5, yPos + (int)(mHeaderH / 2), mLastHeaderValue.c_str(), mFont->GetResource(), mRenderW, TEXT_ONLY_RIGHT, 0);
		}

		// Add the separator
		gr_color(mHeaderSeparatorColor.red, mHeaderSeparatorColor.green, mHeaderSeparatorColor.blue, mHeaderSeparatorColor.alpha);
		gr_fill(mRenderX, yPos + mHeaderH - mHeaderSeparatorH, mRenderW, mHeaderSeparatorH);
	}

	// reset clipping
	gr_noclip();

	// render fast scroll
	if (hasScroll) {
		int fWidth = mRenderW - listW;
		int fHeight = mRenderH - mHeaderH;
		int centerX = listW + mRenderX + fWidth / 2;

		// first determine the total list height and where we are in the list
		int totalHeight = GetItemCount() * actualItemHeight; // total height of the full list in pixels
		int topPos = firstDisplayedItem * actualItemHeight - y_offset;

		// now scale it proportionally to the scrollbar height
		int boxH = fHeight * fHeight / totalHeight; // proportional height of the displayed portion
		boxH = std::max(boxH, mFastScrollRectH); // but keep a minimum height
		int boxY = (fHeight - boxH) * topPos / (totalHeight - fHeight); // pixels relative to top of list
		int boxW = mFastScrollRectW;

		int x = centerX - boxW / 2;
		int y = mRenderY + mHeaderH + boxY;

		// line above and below box (needs to be split because box can be transparent)
		gr_color(mFastScrollLineColor.red, mFastScrollLineColor.green, mFastScrollLineColor.blue, mFastScrollLineColor.alpha);
		gr_fill(centerX - mFastScrollLineW / 2, mRenderY + mHeaderH, mFastScrollLineW, boxY);
		gr_fill(centerX - mFastScrollLineW / 2, y + boxH, mFastScrollLineW, fHeight - boxY - boxH);

		// box
		gr_color(mFastScrollRectColor.red, mFastScrollRectColor.green, mFastScrollRectColor.blue, mFastScrollRectColor.alpha);
		gr_fill(x, y, boxW, boxH);

		mFastScrollRectCurrentY = boxY;
		mFastScrollRectCurrentH = boxH;
	}
	mUpdate = 0;
	return 0;
}

void GUIScrollList::RenderItem(size_t itemindex __unused, int yPos, bool selected)
{
	RenderStdItem(yPos, selected, NULL, "implement RenderItem!");
}

void GUIScrollList::RenderStdItem(int yPos, bool selected, ImageResource* icon, const char* text, int iconAndTextH)
{
	if (hasHighlightColor && selected) {
		// Highlight the item background of the selected item
		gr_color(mHighlightColor.red, mHighlightColor.green, mHighlightColor.blue, mHighlightColor.alpha);
		gr_fill(mRenderX, yPos, mRenderW, actualItemHeight);
	}

	if (selected) {
		// Use the highlight color for the font
		gr_color(mFontHighlightColor.red, mFontHighlightColor.green, mFontHighlightColor.blue, mFontHighlightColor.alpha);
	} else {
		// Set the color for the font
		gr_color(mFontColor.red, mFontColor.green, mFontColor.blue, mFontColor.alpha);
	}

	if (!iconAndTextH)
		iconAndTextH = actualItemHeight;

	// render icon
	if (icon && icon->GetResource()) {
		int iconH = icon->GetHeight();
		int iconW = icon->GetWidth();
		int iconY = yPos + (iconAndTextH - iconH) / 2;
		int iconX = mRenderX + (maxIconWidth - iconW) / 2;
		gr_blit(icon->GetResource(), 0, 0, iconW, iconH, iconX, iconY);
	}

	// render label text
	if (mFont && mFont->GetResource()) {
		int textX = mRenderX + maxIconWidth + 5;
		int textY = yPos + (iconAndTextH / 2);
		gr_textEx_scaleW(textX, textY, text, mFont->GetResource(), mRenderW, TEXT_ONLY_RIGHT, 0);
	}
}

int GUIScrollList::Update(void)
{
	if (!isConditionTrue())
		return 0;

	if (!mHeaderIsStatic) {
		std::string newValue = gui_parse_text(mHeaderText);
		if (mLastHeaderValue != newValue) {
			mLastHeaderValue = newValue;
			mUpdate = 1;
		}
	}

	// Handle kinetic scrolling
	// maximum number of items to scroll per update
	float maxItemsScrolledPerFrame = std::max(2.5, float(GetDisplayItemCount() / 4) + 0.5);

	int maxScrollDistance = actualItemHeight * maxItemsScrolledPerFrame;
	int oldScrollingSpeed = scrollingSpeed;
	if (scrollingSpeed == 0) {
		// Do nothing
		return 0;
	} else if (scrollingSpeed > 0) {
		if (scrollingSpeed < maxScrollDistance)
			y_offset += scrollingSpeed;
		else
			y_offset += maxScrollDistance;
		scrollingSpeed *= SCROLLING_SPEED_DECREMENT;
		if (scrollingSpeed == oldScrollingSpeed)
			--scrollingSpeed;
	} else if (scrollingSpeed < 0) {
		if (abs(scrollingSpeed) < maxScrollDistance)
			y_offset += scrollingSpeed;
		else
			y_offset -= maxScrollDistance;
		scrollingSpeed *= SCROLLING_SPEED_DECREMENT;
		if (scrollingSpeed == oldScrollingSpeed)
			++scrollingSpeed;
	}
	if (abs(scrollingSpeed) < SCROLLING_FLOOR)
		scrollingSpeed = 0;
	HandleScrolling();
	mUpdate = 1;

	return 0;
}

size_t GUIScrollList::HitTestItem(int x __unused, int y)
{
	// We only care about y position
	if (y < mRenderY || y - mRenderY <= mHeaderH || y - mRenderY > mRenderH)
		return NO_ITEM;

	int startSelection = (y - mRenderY - mHeaderH);

	// Locate the correct item
	size_t actualSelection = firstDisplayedItem;
	int selectY = y_offset;
	while (selectY + actualItemHeight < startSelection) {
		selectY += actualItemHeight;
		actualSelection++;
	}

	if (actualSelection < GetItemCount())
		return actualSelection;

	return NO_ITEM;
}

int GUIScrollList::NotifyTouch(TOUCH_STATE state, int x, int y)
{
	if (!isConditionTrue())
		return -1;

	switch (state)
	{
	case TOUCH_START:
		if (hasScroll && x >= mRenderX + mRenderW - mFastScrollW) {
			fastScroll = 1; // Initial touch is in the fast scroll region
			int fastScrollBoxTop = mFastScrollRectCurrentY + mRenderY + mHeaderH;
			int fastScrollBoxBottom = fastScrollBoxTop + mFastScrollRectCurrentH;
			if (y >= fastScrollBoxTop && y < fastScrollBoxBottom)
				// user grabbed the fastscroll bar
				// try to keep the initially touched part of the scrollbar under the finger
				mFastScrollRectTouchY = y - fastScrollBoxTop;
			else
				// user tapped outside the fastscroll bar
				// center fastscroll rect on the initial touch position
				mFastScrollRectTouchY = mFastScrollRectCurrentH / 2;
		}

		if (scrollingSpeed != 0) {
			selectedItem = NO_ITEM; // this allows the user to tap the list to stop the scrolling without selecting the item they tap
			scrollingSpeed = 0; // stop scrolling on a new touch
		} else if (!fastScroll && allowSelection) {
			// find out which item the user touched
			selectedItem = HitTestItem(x, y);
		}
		if (selectedItem != NO_ITEM)
			mUpdate = 1;
		lastY = last2Y = y;
		break;

	case TOUCH_DRAG:
		if (fastScroll)
		{
			int relY = y - mRenderY - mHeaderH; // touch position relative to window
			int windowH = mRenderH - mHeaderH;
			int totalHeight = GetItemCount() * actualItemHeight; // total height of the full list in pixels

			// calculate new top position of the fastscroll bar relative to window
			int newY = relY - mFastScrollRectTouchY;
			// keep it fully inside the list
			newY = std::min(std::max(newY, 0), windowH - mFastScrollRectCurrentH);

			// now compute the new scroll position for the list
			int newTopPos = newY * (totalHeight - windowH) / (windowH - mFastScrollRectCurrentH); // new top pixel of list
			newTopPos = std::min(newTopPos, totalHeight - windowH); // account for rounding errors
			firstDisplayedItem = newTopPos / actualItemHeight;
			y_offset = - newTopPos % actualItemHeight;

			selectedItem = NO_ITEM;
			mUpdate = 1;
			scrollingSpeed = 0; // prevent kinetic scrolling when using fast scroll
			break;
		}

		// Provide some debounce on initial touches
		if (selectedItem != NO_ITEM && abs(y - lastY) < touchDebounce) {
			mUpdate = 1;
			break;
		}

		selectedItem = NO_ITEM; // nothing is selected because we dragged too far
		// Handle scrolling
		if (hasScroll) {
			y_offset += y - lastY; // adjust the scrolling offset based on the difference between the starting touch and the current touch
			last2Y = lastY; // keep track of previous y locations so that we can tell how fast to scroll for kinetic scrolling
			lastY = y; // update last touch to the current touch so we can tell how far and what direction we scroll for the next touch event

			HandleScrolling();
		} else
			y_offset = 0;
		mUpdate = 1;
		break;

	case TOUCH_RELEASE:
		if (fastScroll)
			mUpdate = 1; // get rid of touch effects on the fastscroll bar
		fastScroll = 0;
		if (selectedItem != NO_ITEM) {
			// We've selected an item!
			NotifySelect(selectedItem);
			mUpdate = 1;

			DataManager::Vibrate("tw_button_vibrate");
			selectedItem = NO_ITEM;
		} else {
			// Start kinetic scrolling
			scrollingSpeed = lastY - last2Y;
			if (abs(scrollingSpeed) < touchDebounce)
				scrollingSpeed = 0;
		}
	case TOUCH_REPEAT:
	case TOUCH_HOLD:
		break;
	}
	return 0;
}

void GUIScrollList::HandleScrolling()
{
	// handle dragging downward, scrolling upward
	// the offset should always be <= 0 and > -actualItemHeight, adjust the first display row and offset as needed
	while (firstDisplayedItem && y_offset > 0) {
		firstDisplayedItem--;
		y_offset -= actualItemHeight;
	}
	if (firstDisplayedItem == 0 && y_offset > 0) {
		y_offset = 0; // user kept dragging downward past the top of the list, so always reset the offset to 0 since we can't scroll any further in this direction
		scrollingSpeed = 0; // stop kinetic scrolling
	}

	// handle dragging upward, scrolling downward
	int totalSize = GetItemCount();
	int lines = GetDisplayItemCount(); // number of full lines our list can display at once
	int bottom_offset = GetDisplayRemainder() - actualItemHeight; // extra display area that can display a partial line for per pixel scrolling

	// the offset should always be <= 0 and > -actualItemHeight, adjust the first display row and offset as needed
	while (firstDisplayedItem + lines + (bottom_offset ? 1 : 0) < totalSize && abs(y_offset) > actualItemHeight) {
		firstDisplayedItem++;
		y_offset += actualItemHeight;
	}
	// Check if we dragged too far, set the list at the bottom and adjust offset as needed
	if (bottom_offset != 0 && firstDisplayedItem + lines + 1 >= totalSize && y_offset <= bottom_offset) {
		firstDisplayedItem = totalSize - lines - 1;
		y_offset = bottom_offset;
		scrollingSpeed = 0; // stop kinetic scrolling
	} else if (firstDisplayedItem + lines >= totalSize && y_offset < 0) {
		firstDisplayedItem = totalSize - lines;
		y_offset = 0;
		scrollingSpeed = 0; // stop kinetic scrolling
	}
}

int GUIScrollList::GetDisplayItemCount()
{
	return (mRenderH - mHeaderH) / (actualItemHeight);
}

int GUIScrollList::GetDisplayRemainder()
{
	return (mRenderH - mHeaderH) % actualItemHeight;
}

int GUIScrollList::NotifyVarChange(const std::string& varName, const std::string& value)
{
	GUIObject::NotifyVarChange(varName, value);

	if (!isConditionTrue())
		return 0;

	if (!mHeaderIsStatic) {
		std::string newValue = gui_parse_text(mHeaderText);
		if (mLastHeaderValue != newValue) {
			mLastHeaderValue = newValue;
			firstDisplayedItem = 0;
			y_offset = 0;
			scrollingSpeed = 0; // stop kinetic scrolling on variable changes
			mUpdate = 1;
		}
	}
	return 0;
}

int GUIScrollList::SetRenderPos(int x, int y, int w /* = 0 */, int h /* = 0 */)
{
	mRenderX = x;
	mRenderY = y;
	if (w || h)
	{
		mRenderW = w;
		mRenderH = h;
	}
	SetActionPos(mRenderX, mRenderY, mRenderW, mRenderH);
	mUpdate = 1;
	return 0;
}

void GUIScrollList::SetPageFocus(int inFocus)
{
	if (inFocus) {
		NotifyVarChange("", ""); // This forces a check for the header text
		scrollingSpeed = 0; // stop kinetic scrolling on page changes
		mUpdate = 1;
	}
}

bool GUIScrollList::AddLines(std::vector<std::string>* origText, std::vector<std::string>* origColor, size_t* lastCount, std::vector<std::string>* rText, std::vector<std::string>* rColor)
{
	if (!mFont || !mFont->GetResource())
		return false;
	if (*lastCount == origText->size())
		return false; // nothing to add

	size_t prevCount = *lastCount;
	*lastCount = origText->size();

	// Due to word wrap, figure out what / how the newly added text needs to be added to the render vector that is word wrapped
	// Note, that multiple consoles on different GUI pages may be different widths or use different fonts, so the word wrapping
	// may different in different console windows
	for (size_t i = prevCount; i < *lastCount; i++) {
		string curr_line = origText->at(i);
		string curr_color;
		if (origColor)
			curr_color = origColor->at(i);
		for (;;) {
			size_t line_char_width = gr_ttf_maxExW(curr_line.c_str(), mFont->GetResource(), mRenderW);
			if (line_char_width < curr_line.size()) {
				//string left = curr_line.substr(0, line_char_width);
				size_t wrap_pos = curr_line.find_last_of(" ,./:-_;", line_char_width - 1);
				if (wrap_pos == string::npos)
					wrap_pos = line_char_width;
				else if (wrap_pos < line_char_width - 1)
					wrap_pos++;
				rText->push_back(curr_line.substr(0, wrap_pos));
				if (origColor)
					rColor->push_back(curr_color);
				curr_line = curr_line.substr(wrap_pos);
				/* After word wrapping, delete any leading spaces. Note that the word wrapping is not smart enough to know not
				 * to wrap in the middle of something like ... so some of the ... could appear on the following line. */
				curr_line.erase(0, curr_line.find_first_not_of(" "));
			} else {
				rText->push_back(curr_line);
				if (origColor)
					rColor->push_back(curr_color);
				break;
			}
		}
	}
	return true;
}