libui/examples/drawtext/emptystr_hittest.c

// 20 january 2017
#include "drawtext.h"

// TODO FOR THIS FILE
// get rid of it once we rewrite this example (which requires having more fine-grained scrolling control)

// TODO double-check ligatures on all platforms to make sure we can place the cursor at the right place
// TODO the hiding and showing does not work properly on GTK+
// TODO using the arrow keys allows us to walk back to the end of the line on some platforms (TODO which?); IIRC arrow keys shouldn't do that
// TODO make sure to check the cursor positions of RTL on all platforms

static const char *text = "";
static char fontFamily[] = "Helvetica";
static uiDrawFontDescriptor defaultFont = {
	.Family = fontFamily,
	.Size = 14,
	.Weight = uiDrawTextWeightNormal,
	.Italic = uiDrawTextItalicNormal,
	.Stretch = uiDrawTextStretchNormal,
};
static uiAttributedString *attrstr;
static uiDrawTextLayoutParams params;

#define margins 10

static uiBox *panel;
static uiBox *vbox;
static uiLabel *caretLabel;
static uiCheckbox *showLineBounds;
static uiFontButton *fontButton;
static uiCombobox *textAlign;

static int caretLine = -1;
static size_t caretPos;

// TODO should be const?
static uiDrawBrush fillBrushes[4] = {
	{
		.Type = uiDrawBrushTypeSolid,
		.R = 1.0,
		.G = 0.0,
		.B = 0.0,
		.A = 0.5,
	},
	{
		.Type = uiDrawBrushTypeSolid,
		.R = 0.0,
		.G = 1.0,
		.B = 0.0,
		.A = 0.5,
	},
	{
		.Type = uiDrawBrushTypeSolid,
		.R = 0.0,
		.G = 0.0,
		.B = 1.0,
		.A = 0.5,
	},
	{
		.Type = uiDrawBrushTypeSolid,
		.R = 0.0,
		.G = 1.0,
		.B = 1.0,
		.A = 0.5,
	},
};

static void draw(uiAreaDrawParams *p)
{
	uiDrawPath *path;
	uiDrawTextLayout *layout;
	uiDrawTextLayoutLineMetrics m;

	// only clip the text, not the guides
	uiDrawSave(p->Context);

	path = uiDrawNewPath(uiDrawFillModeWinding);
	uiDrawPathAddRectangle(path, margins, margins,
		p->AreaWidth - 2 * margins,
		p->AreaHeight - 2 * margins);
	uiDrawPathEnd(path);
	uiDrawClip(p->Context, path);
	uiDrawFreePath(path);

	params.Width = p->AreaWidth - 2 * margins;
	layout = uiDrawNewTextLayout(&params);
	uiDrawText(p->Context, layout, margins, margins);

	uiDrawRestore(p->Context);

	if (caretLine == -1) {
		caretLine = uiDrawTextLayoutNumLines(layout) - 1;
		caretPos = uiAttributedStringLen(attrstr);
	}
	uiDrawCaret(p->Context, margins, margins,
		layout, caretPos, &caretLine);

	if (uiCheckboxChecked(showLineBounds)) {
		int i, n;
		int fill = 0;

		n = uiDrawTextLayoutNumLines(layout);
		for (i = 0; i < n; i++) {
			uiDrawTextLayoutLineGetMetrics(layout, i, &m);
			path = uiDrawNewPath(uiDrawFillModeWinding);
			uiDrawPathAddRectangle(path, margins + m.X, margins + m.Y,
				m.Width, m.Height);
			uiDrawPathEnd(path);
			uiDrawFill(p->Context, path, fillBrushes + fill);
			uiDrawFreePath(path);
			fill = (fill + 1) % 4;
		}
	}

	uiDrawFreeTextLayout(layout);
}

static void mouse(uiAreaMouseEvent *e)
{
	uiDrawTextLayout *layout;
	char labelText[128];

	if (e->Down != 1)
		return;

	params.Width = e->AreaWidth - 2 * margins;
	layout = uiDrawNewTextLayout(&params);
	uiDrawTextLayoutHitTest(layout,
		e->X - margins, e->Y - margins,
		&caretPos, &caretLine);
	uiDrawFreeTextLayout(layout);

	// TODO move this into the draw handler so it is reflected by keyboard-based position changes
	// urgh %zd is not supported by MSVC with sprintf()
	// TODO get that part in test/ about having no other option
	sprintf(labelText, "pos %d line %d",
		(int) caretPos, caretLine);
	uiLabelSetText(caretLabel, labelText);

	redraw();
}

static int key(uiAreaKeyEvent *e)
{
	size_t grapheme;

	if (e->Up)
		return 0;
	if (e->Key != 0)
		return 0;
	switch (e->ExtKey) {
	case uiExtKeyUp:
		// TODO
		return 1;
	case uiExtKeyDown:
		// TODO
		return 1;
	case uiExtKeyLeft:
		grapheme = uiAttributedStringByteIndexToGrapheme(attrstr, caretPos);
		if (grapheme == 0)
			return 0;
		grapheme--;
		caretPos = uiAttributedStringGraphemeToByteIndex(attrstr, grapheme);
		redraw();
		return 1;
	case uiExtKeyRight:
		grapheme = uiAttributedStringByteIndexToGrapheme(attrstr, caretPos);
		if (grapheme == uiAttributedStringNumGraphemes(attrstr))
			return 0;
		grapheme++;
		caretPos = uiAttributedStringGraphemeToByteIndex(attrstr, grapheme);
		redraw();
		return 1;
	}
	return 0;
}

static struct example hitTestExample;

// TODO share?
static void checkboxChecked(uiCheckbox *c, void *data)
{
	redraw();
}

static void changeFont(uiFontButton *b, void *data)
{
	if (defaultFont.Family != fontFamily)
		uiFreeText(defaultFont.Family);
	// TODO rename defaultFont
	uiFontButtonFont(fontButton, &defaultFont);
	printf("{\n\tfamily: %s\n\tsize: %g\n\tweight: %d\n\titalic: %d\n\tstretch: %d\n}\n",
		defaultFont.Family,
		defaultFont.Size,
		(int) (defaultFont.Weight),
		(int) (defaultFont.Italic),
		(int) (defaultFont.Stretch));
	redraw();
}

static void changeTextAlign(uiCombobox *c, void *data)
{
	// note the order of the items added below
	params.Align = (uiDrawTextLayoutAlign) uiComboboxSelected(textAlign);
	redraw();
}

// TODO share?
static uiCheckbox *newCheckbox(uiBox *box, const char *text)
{
	uiCheckbox *c;

	c = uiNewCheckbox(text);
	uiCheckboxOnToggled(c, checkboxChecked, NULL);
	uiBoxAppend(box, uiControl(c), 0);
	return c;
}

struct example *mkEmptyStringExample(void)
{
	panel = uiNewHorizontalBox();
	vbox = uiNewVerticalBox();
	// TODO the second vbox causes this not to stretch at least on OS X
	uiBoxAppend(panel, uiControl(vbox), 1);
	caretLabel = uiNewLabel("Caret information is shown here");
	uiBoxAppend(vbox, uiControl(caretLabel), 0);
	showLineBounds = newCheckbox(vbox, "Show Line Bounds (for debugging metrics)");
	vbox = uiNewVerticalBox();
	uiBoxAppend(panel, uiControl(vbox), 0);
	fontButton = uiNewFontButton();
	uiFontButtonOnChanged(fontButton, changeFont, NULL);
	// TODO set the font button to the current defaultFont
	uiBoxAppend(vbox, uiControl(fontButton), 0);
	textAlign = uiNewCombobox();
	// note that these are in the order in the enum
	uiComboboxAppend(textAlign, "Left");
	uiComboboxAppend(textAlign, "Center");
	uiComboboxAppend(textAlign, "Right");
	uiComboboxOnSelected(textAlign, changeTextAlign, NULL);
	uiBoxAppend(vbox, uiControl(textAlign), 0);

	hitTestExample.name = "Empty String";
	hitTestExample.panel = uiControl(panel);
	hitTestExample.draw = draw;
	hitTestExample.mouse = mouse;
	hitTestExample.key = key;

	attrstr = uiNewAttributedString(text);
	params.String = attrstr;
	params.DefaultFont = &defaultFont;
	params.Align = uiDrawTextLayoutAlignLeft;

	return &hitTestExample;
}