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| Calculator - Step 4. Improve on User Interface |
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Objective for this step
Once we have the core business logic, and foolproofed the application, we can start improving the user interface (UI), such as making it nicer, or giving a better user experience.
Here are a few examples:
- Change this to a 4 or 8 line display so that user can see clearly what has been entered earlier
- Store the results in a history and allowing user to refer back or use any result in the history
- Allow user to change past entry, e.g. the user entered 123+457, press the '=' sign, and realized that it should be 123+456. The user can press a button, go back to edit 457 to 456, and then press the '=' sign.
As mentioned earlier, the focus here is php-gtk2, and not the mechanics of the application itself. So we will only add a few cosmetic changes to the calculator here.
The Code
Note: If you have installed php-gtk2 using Gnope Installer on Windows, and if running the sample code below gives you warning that the Symbolic names for keys (e.g. Gdk::KEY_Return) is not defined, you might want to update your php-gtk2 with the latest php-gtk2.dll available here. Simply download the php-gtk2.dll and replace the copy in the folder php-gtk2\ext. The latest compilation has put in the Symbolic names for keys listed here. 1
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| <?php
class Calculator{
var $operator = '';
var $stack = array();
var $is_entering_number = 0;
// constructor
function Calculator() {
}
function main() {
$this->setup_window();
$this->setup_layout();
$this->window->show_all(); // display the calculator
Gtk::main(); // and let's go!
}
function setup_window() {
$this->window = new GtkWindow();
$this->window->set_size_request(200, 240);
$this->window->connect_simple('destroy', array('Gtk','main_quit'));
$this->window->connect('key-press-event', array(&$this, "on_keypress"));
}
function setup_layout() {
// setup a vbox to hold display and buttons
$vbox = new GtkVBox();
$this->window->add($vbox);
// setup display
$this->display = new GtkEntry();
$this->display->set_alignment(1.0); // right-justified
$this->display->set_editable(false); // for display only
$vbox->pack_start($this->display);
// the button labels
$button_label = array(
array('BackSpc', 'CE', 'C'),
array('7', '8', '9', '/', 'sqrt'),
array('4', '5', '6', '*', '%'),
array('1', '2', '3', '-', '1/x'),
array('0', '+/-', '.', '+', '=')
);
// setup the buttons
for ($j=0; $j<5; ++$j) {
$hbox = new GtkHBox();
$vbox->pack_start($hbox); // use a hbox to hold each row of buttons
for ($i=0; $i<5; ++$i) {
if ($j==0 && $i>2) continue; // first row contains only 3 buttons
$value = $button_label[$j][$i];
$button = new GtkButton($value);
$button->set_size_request(40, 32); // set the size
$button->connect('clicked', array(&$this, "on_button"));
if (preg_match("/^([0-9]|\.)$/", $value)) // digits
$button->modify_bg(Gtk::STATE_NORMAL, GdkColor::parse('#FFFF33'));
if (preg_match("/^(\+|-|\*|\/){1}$/", $value)) // +-*/
$button->modify_bg(Gtk::STATE_NORMAL, GdkColor::parse('#ff99ff'));
if ($value=='C' || $value=='CE') // Clear
$button->modify_bg(Gtk::STATE_NORMAL, GdkColor::parse('#FF3366'));
if ($value=='=') // =
$button->modify_bg(Gtk::STATE_NORMAL, GdkColor::parse('#0099FF'));
$hbox->pack_start($button);
}
}
}
// process button click
function on_button($button) {
$value = $button->child->get_text();
echo "button_click: $value\n";
$this->process_input($value);
}
// process keyboard input
function on_keypress($widget, $event) {
$keyval = $event->keyval;
$value = chr($keyval); // get the ASCII equivalent
if (preg_match("/[0-9\+\-\*\/\.=]/", $value) || $keyval==Gdk::KEY_Return || $keyval==Gdk::KEY_BackSpace) {
if ($keyval==Gdk::KEY_Return) $value='=';
if ($keyval==Gdk::KEY_BackSpace) $value='BackSpc';
$this->process_input($value);
$this->display->set_position(-1); // move the cursor to the end of display
}
}
// process input
function process_input($value) {
if (preg_match("/^([0-9]|\.)$/", $value)) {
$number = array_pop($this->stack);
if (preg_match("/^([0-9]|\.)+$/", $number)) {
if ($value=='.') {
if (strpos($number,'.')===false) $number .= $value;
} else {
$number .= $value;
}
} else {
if ($number!='') array_push($this->stack, $number);
$number = $value;
}
array_push($this->stack, $number);
$this->display->set_text($number);
} elseif (preg_match("/^(\+|-|\*|\/|=){1}$/", $value)) { // perform binary operations
if (count($this->stack)<3) {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack)))
if ($value!='=')
array_push($this->stack, $value);
} else {
$number2 = array_pop($this->stack);
$operator = array_pop($this->stack);
$number1 = array_pop($this->stack);
switch ($operator) {
case '+': $result = $number1 + $number2; break;
case '-': $result = $number1 - $number2; break;
case '*': $result = $number1 * $number2; break;
case '/': $result = $number1 / $number2; break;
}
$this->display->set_text($result);
array_push($this->stack, $result);
if ($value!='=') array_push($this->stack, $value);
}
//process unary operators
} elseif ($value=='1/x' || $value=='sqrt' || $value=='%' || $value=='+/-') {
if (count($this->stack)>=1) {
$number = array_pop($this->stack);
switch ($value) {
case '1/x': $result = 1/$number; break;
case 'sqrt': $result = sqrt($number); break;
case '%': $result = $number / 100; break;
case '+/-': $result = -$number; break;
}
$this->display->set_text($result);
array_push($this->stack, $result);
}
} elseif ($value=='C') {
$this->stack=array();
$this->display->set_text('0');
} elseif ($value=='CE') {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack))) {
$number = array_pop($this->stack);
$this->display->set_text('0');
}
} elseif ($value=='BackSpc') {
if (preg_match("/^([0-9]|\.)+$/", end($this->stack))) {
$number = array_pop($this->stack);
$number = substr($number, 0, strlen($number)-1);
$this->display->set_text($number);
array_push($this->stack, $number);
}
}
$this->show_stack(); // show current stack
}
// prints the current stack content
function show_stack() {
echo "current stack content:\n";
for ($i=count($this->stack)-1; $i>=0; --$i) {
echo "stack[$i] = {$this->stack[$i]}\n";
}
echo "\n";
}
}
$cal = new Calculator(); // cerate a new calculator
$cal->main(); // let's run it!
?> |
Sample Output
Links
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Search PHP-GTK2 Manual
Full-text search on php-gtk2 manual
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