A simple pager implemented on top of the generic text console interface.

git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35812 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/boot/loader/pager.cpp

@@ -0,0 +1,207 @@
+/*
+ * Copyright 2010, Ingo Weinhold, ingo_weinhold@gmx.de.
+ * Distributed under the terms of the MIT License.
+ */
+
+
+#include "pager.h"
+
+#include <ctype.h>
+#include <string.h>
+
+#include <algorithm>
+
+#include <boot/platform/generic/text_console.h>
+
+
+// #pragma mark - PagerTextSource
+
+
+PagerTextSource::~PagerTextSource()
+{
+}
+
+
+// #pragma mark -
+
+
+static size_t
+next_line(const PagerTextSource& textSource, size_t width, size_t offset,
+	char* buffer, size_t bufferSize)
+{
+	size_t bytesRead = textSource.Read(offset, buffer, bufferSize - 1);
+	if (bytesRead == 0)
+		return 0;
+
+	buffer[bytesRead] = '\0';
+
+	// replace all '\0's by spaces
+	for (size_t i = 0; i < bytesRead; i++) {
+		if (buffer[i] == '\0')
+			buffer[i] = ' ';
+	}
+
+	if (const char* lineEnd = strchr(buffer, '\n'))
+		bytesRead = lineEnd - buffer;
+
+	if (bytesRead > (size_t)width)
+		bytesRead = width;
+
+	// replace unprintables by '.'
+	for (size_t i = 0; i < bytesRead; i++) {
+		if (!isprint(buffer[i]))
+			buffer[i] = '.';
+	}
+
+	bool lineBreak = buffer[bytesRead] == '\n';
+
+	buffer[bytesRead] = '\0';
+
+	return bytesRead + (lineBreak ? 1 : 0);
+}
+
+
+static int32
+count_lines(const PagerTextSource& textSource, size_t width, char* buffer,
+	size_t bufferSize)
+{
+	int32 lineCount = 0;
+	size_t offset = 0;
+
+	while (true) {
+		size_t bytesRead = next_line(textSource, width, offset, buffer,
+			bufferSize);
+		if (bytesRead == 0)
+			break;
+
+		offset += bytesRead;
+		lineCount++;
+	}
+
+	return lineCount;
+}
+
+
+static size_t
+offset_of_line(const PagerTextSource& textSource, size_t width, char* buffer,
+	size_t bufferSize, int32 line)
+{
+	int32 lineCount = 0;
+	size_t offset = 0;
+
+	while (true) {
+		if (line == lineCount)
+			return offset;
+
+		size_t bytesRead = next_line(textSource, width, offset, buffer,
+			bufferSize);
+		if (bytesRead == 0)
+			break;
+
+		offset += bytesRead;
+		lineCount++;
+	}
+
+	return offset;
+}
+
+
+// #pragma mark -
+
+
+void
+pager(const PagerTextSource& textSource)
+{
+	console_set_cursor(0, 0);
+
+	int32 width = console_width();
+	int32 height = console_height();
+
+	char lineBuffer[256];
+
+	int32 lineCount = count_lines(textSource, width, lineBuffer,
+		sizeof(lineBuffer));
+	int32 topLine = 0;
+
+	bool quit = false;
+	while (!quit) {
+		// get the text offset for the top line
+		size_t offset = offset_of_line(textSource, width, lineBuffer,
+			sizeof(lineBuffer), topLine);
+
+		// clear the screen and print the lines
+		console_clear_screen();
+
+		int32 screenLine = 0;
+		while (screenLine + 1 < height) {
+			size_t bytesRead = next_line(textSource, width, offset, lineBuffer,
+				sizeof(lineBuffer));
+			if (bytesRead == 0)
+				break;
+
+			console_set_cursor(0, screenLine);
+			puts(lineBuffer);
+
+			offset += bytesRead;
+			screenLine++;
+		}
+
+		// print the statistics line at the bottom
+		console_set_cursor(0, height - 1);
+		console_set_color(BLACK, WHITE);
+		int32 bottomLine = std::min(topLine + height - 2, lineCount - 1);
+		printf("%" B_PRIuSIZE " - %" B_PRIuSIZE "  %" B_PRIuSIZE "%%",
+			topLine, bottomLine, (bottomLine + 1) * 100 / lineCount);
+		console_set_color(WHITE, BLACK);
+
+		// wait for a key that changes the position
+		int32 previousTopLine = topLine;
+
+		while (!quit && topLine == previousTopLine) {
+			switch (console_wait_for_key()) {
+				case TEXT_CONSOLE_KEY_ESCAPE:
+				case 'q':
+				case 'Q':
+					// quit
+					quit = true;
+					break;
+
+				case TEXT_CONSOLE_KEY_DOWN:
+				case TEXT_CONSOLE_KEY_RETURN:
+					// next line
+					topLine++;
+					break;
+
+				case TEXT_CONSOLE_KEY_UP:
+					// previous line
+					topLine--;
+					break;
+
+				case TEXT_CONSOLE_KEY_PAGE_UP:
+					// previous page
+					topLine -= height - 1;
+					break;
+
+				case TEXT_CONSOLE_KEY_PAGE_DOWN:
+					// next page
+					topLine += height - 1;
+					break;
+
+				case TEXT_CONSOLE_KEY_HOME:
+					// beginning of text
+					topLine = 0;
+					break;
+
+				case TEXT_CONSOLE_KEY_END:
+					// end of text
+					topLine = lineCount;
+					break;
+			}
+
+			if (topLine > lineCount - (height - 1))
+				topLine = lineCount - (height - 1);
+			if (topLine < 0)
+				topLine = 0;
+		}
+	}
+}

src/system/boot/loader/pager.h

@@ -0,0 +1,25 @@
+/*
+ * Copyright 2010, Ingo Weinhold, ingo_weinhold@gmx.de.
+ * Distributed under the terms of the MIT License.
+ */
+#ifndef PAGER_H
+#define PAGER_H
+
+
+#include <SupportDefs.h>
+
+
+class PagerTextSource {
+public:
+	virtual						~PagerTextSource();
+
+	virtual	size_t				BytesAvailable() const = 0;
+	virtual	size_t				Read(size_t offset, void* buffer,
+									size_t size) const = 0;
+};
+
+
+void	pager(const PagerTextSource& textSource);
+
+
+#endif	// PAGER_H