PlaceholderTextView.cpp

/*
 * PlaceholderTextView.cpp - BTextView with placeholder text support
 * Distributed under the terms of the MIT License.
 */

#include "PlaceholderTextView.h"
#include "SearchBarView.h"

#include <Window.h>


PlaceholderTextView::PlaceholderTextView(const char* name, uint32 flags)
	:
	BTextView(name, flags),
	fPlaceholder(),
	fTarget(),
	fModificationMessage(NULL),
	fInvokeMessage(NULL)
{
}


PlaceholderTextView::~PlaceholderTextView()
{
	delete fModificationMessage;
	delete fInvokeMessage;
}


void
PlaceholderTextView::Draw(BRect updateRect)
{
	BTextView::Draw(updateRect);
	_DrawPlaceholder();
}


void
PlaceholderTextView::MakeFocus(bool focus)
{
	BTextView::MakeFocus(focus);
	// Redraw to show/hide placeholder text. Also invalidate parent
	// (SearchTextControl) so it redraws the focus ring around us.
	Invalidate();
	if (Parent())
		Parent()->Invalidate();
}


void
PlaceholderTextView::KeyDown(const char* bytes, int32 numBytes)
{
	if (numBytes == 1 && bytes[0] == B_ESCAPE) {
		// Trigger the clear action on our parent SearchTextControl
		SearchTextControl* control =
			dynamic_cast<SearchTextControl*>(Parent());
		if (control != NULL) {
			control->TriggerClear();
			// The clear action commits the empty state, so sync our
			// tracker to avoid a redundant invoke on the next Tab.
			fLastCommittedText.SetTo("");
		}
		return;
	}
	if (numBytes == 1 && bytes[0] == B_TAB) {
		// Navigate to the next/previous tab stop within our SearchBarView
		// ancestor instead of inserting a tab character.
		// Commit the current field first (same as pressing Enter) so the
		// search executes before focus moves away — but only if the text
		// has actually changed since the last commit, otherwise the email
		// list reloads unnecessarily and steals focus from the target widget.
		BString currentText = Text();
		if (currentText != fLastCommittedText
			&& fInvokeMessage != NULL && fTarget.IsValid()) {
			fLastCommittedText = currentText;
			BMessage message(*fInvokeMessage);
			fTarget.SendMessage(&message);
		}
		// Check for Shift modifier (reverse tab).
		// Read from the window's current B_KEY_DOWN message rather than
		// polling ::modifiers(), which can miss a fast Shift release —
		// especially after the invoke message send above adds latency.
		int32 mods = 0;
		BWindow* window = Window();
		if (window != NULL) {
			BMessage* msg = window->CurrentMessage();
			if (msg != NULL)
				msg->FindInt32("modifiers", &mods);
		}
		bool forward = (mods & B_SHIFT_KEY) == 0;

		// Walk up to the SearchBarView ancestor and use its tab order
		BView* ancestor = Parent();
		while (ancestor != NULL
			&& strcmp(ancestor->Name(), "search_bar") != 0)
			ancestor = ancestor->Parent();
		SearchBarView* searchBar = dynamic_cast<SearchBarView*>(ancestor);
		if (searchBar != NULL)
			searchBar->FocusNextTabStop(this, forward);
		return;
	}
	if (numBytes == 1 && bytes[0] == B_ENTER) {
		// Send invoke message on Enter
		if (fInvokeMessage != NULL && fTarget.IsValid()) {
			fLastCommittedText = Text();
			BMessage message(*fInvokeMessage);
			fTarget.SendMessage(&message);
		}
		return;  // Don't insert newline
	}
	BTextView::KeyDown(bytes, numBytes);
}


void
PlaceholderTextView::InsertText(const char* text, int32 length,
	int32 offset, const text_run_array* runs)
{
	BTextView::InsertText(text, length, offset, runs);
	_SendModificationMessage();
	Invalidate();  // Redraw for placeholder
}


void
PlaceholderTextView::DeleteText(int32 fromOffset, int32 toOffset)
{
	BTextView::DeleteText(fromOffset, toOffset);
	_SendModificationMessage();
	Invalidate();  // Redraw for placeholder
}


void
PlaceholderTextView::SetPlaceholder(const char* placeholder)
{
	fPlaceholder = placeholder;
	Invalidate();
}


void
PlaceholderTextView::SetTarget(BMessenger messenger)
{
	fTarget = messenger;
}


void
PlaceholderTextView::SetModificationMessage(BMessage* message)
{
	delete fModificationMessage;
	fModificationMessage = message;
}


void
PlaceholderTextView::SetInvokeMessage(BMessage* message)
{
	delete fInvokeMessage;
	fInvokeMessage = message;
}


void
PlaceholderTextView::_DrawPlaceholder()
{
	// Only draw placeholder when empty
	if (TextLength() > 0 || fPlaceholder.IsEmpty())
		return;

	// Get text rect and font metrics
	BRect textRect = TextRect();
	font_height fh;
	GetFontHeight(&fh);
	
	// If text rect looks wrong (too narrow), use bounds instead
	// (can happen before layout is fully complete)
	if (textRect.Width() < 10) {
		textRect = Bounds();
		textRect.InsetBy(2, 1);
	}

	// Calculate baseline position
	float y = textRect.top + fh.ascent;

	// Use disabled text color for placeholder
	rgb_color viewColor = ViewColor();
	rgb_color placeholderColor = tint_color(viewColor, B_DISABLED_LABEL_TINT);

	// Draw placeholder text
	SetHighColor(placeholderColor);
	DrawString(fPlaceholder.String(), BPoint(textRect.left, y));
}


void
PlaceholderTextView::_SendModificationMessage()
{
	if (fModificationMessage != NULL && fTarget.IsValid()) {
		BMessage message(*fModificationMessage);
		fTarget.SendMessage(&message);
	}
}