MIT App Inventor: تطوير تطبيق Visit_SA_App - كتاب هندسة البرمجيات - الصف 12 - الفصل 1 - المملكة العربية السعودية

MIT APP INVENTOR Projects Connect Build Settings Help Visit_SA_App Cities Add Screen Remove Screen Publish to Gallery Blocks Viewer Built-in Control Logic Math Text Lists Dictionaries Colors initialize global selection to "" join length Variables Procedures Cities discover_label VerticalArrangement1 cities_label riyadh_list jeddah_list Any component when riyadh_list .AfterPicking do when riyadh_list .BeforePicking do when riyadh_list .GotFocus do when riyadh_list .LostFocus do initialize global name to get set to initialize local name to in when riyadh_list .AfterPicking do set global selection to وزارة التعليم Ministry of Education 2025 - 1447 164 --- VISUAL CONTEXT --- **DIAGRAM**: MIT App Inventor Blocks Editor - Global Variable Initialization Description: A screenshot of the MIT App Inventor Blocks editor showing the 'Built-in' categories (Control, Logic, Math, Text, Lists, Dictionaries, Colors) on the left. On the right, a block for initializing a global variable named 'selection' to an empty string is shown. This block is 'initialize global selection to' and it is connected to a pink text block containing an empty string literal ('""'). Other pink blocks like 'join' and 'length' are also visible but not connected. A blue circle with the number '2' points from the empty string block to the 'initialize global selection to' block, indicating a connection or a step in a tutorial. Context: This diagram illustrates how to declare and initialize a global variable named 'selection' with an empty string value in MIT App Inventor, a fundamental step in setting up variables for an application. **DIAGRAM**: MIT App Inventor Blocks Editor - Riyadh List Event Handlers Description: A screenshot of the MIT App Inventor Blocks editor. The left panel shows 'Built-in' categories and 'Cities' components, including 'riyadh_list' and 'jeddah_list'. The main workspace displays several event handler blocks for the 'riyadh_list' component: 'when riyadh_list .AfterPicking do', 'when riyadh_list .BeforePicking do', 'when riyadh_list .GotFocus do', and 'when riyadh_list .LostFocus do'. An identical 'when riyadh_list .AfterPicking do' block is shown isolated on the right side of the workspace. A blue circle with the number '3' points from the 'AfterPicking' block on the left to the isolated one on the right, suggesting a focus on this specific event. Context: This diagram demonstrates various event handlers available for a list picker component ('riyadh_list') in MIT App Inventor, highlighting the 'AfterPicking' event which is crucial for processing user selections from a list. **DIAGRAM**: MIT App Inventor Blocks Editor - Setting Global Selection Description: A screenshot of the MIT App Inventor Blocks editor. The left panel shows 'Built-in' categories and 'Variables' blocks. The main workspace displays several variable-related blocks: 'initialize global name to', 'get', 'set to', and 'initialize local name to in'. On the right, a 'when riyadh_list .AfterPicking do' event block is shown, containing a 'set global selection to' block. A blue circle with the number '4' points from the 'set to' block (from the Variables category) to the 'set global selection to' block within the 'AfterPicking' event, indicating how a variable's value is assigned. Context: This diagram illustrates how to use the 'set global selection to' block within an 'AfterPicking' event handler to update the value of a global variable ('selection') based on user interaction with a list picker, a common pattern for handling user input in App Inventor.