programming your app’s memory 靜宜大學資管系 楊子青

Post on 01-Jan-2016

96 Views

Category:

Documents

0 Downloads

Preview:

Click to see full reader

DESCRIPTION

Programming Your App’s Memory 靜宜大學資管系 楊子青. Memory Slots. Just as people need to remember things, so do apps. When someone tells you the phone number of a pizza place for a onetime immediate call, your brain stores it in a memory slot. - PowerPoint PPT Presentation

TRANSCRIPT

靜宜大學資管系 楊子青 1

Programming Your App’s Memory

靜宜大學資管系 楊子青

靜宜大學資管系 楊子青 2

Memory Slots

• Just as people need to remember things, so do apps.– When someone tells you the phone

number of a pizza place for a onetime immediate call, your brain stores it in a memory slot.

– In this chapter, you’ll learn how to set up an app’s memory, how to store information in it, and how to retrieve that information at a later time.

靜宜大學資管系 楊子青 3

Named Memory Slots

• An app’s memory consists of a set of named memory slots. – Some of these memory slots are created when you

drag a component into your app; these slots are called properties.

– You can also define named memory slots that are not associated with a particular component; these are called variables.

靜宜大學資管系 楊子青 4

1. Properties

• Components (Button, TextBox, and Canvas…)– are part of the user interface.

• Each component is completely defined by a set of properties. – The values stored in the memory slots of each prop

erty determine how the component appears.

靜宜大學資管系 楊子青 5

Modifying the memory slots in the property form to change the app’s appearance

靜宜大學資管系 楊子青 6

2. Variables

• Defining Variables

• Setting and getting a Variable

• Setting a Variable to an Expression– Incrementing a Variable

– Building Complex Expressions

• Displaying Variables

靜宜大學資管系 楊子青 7

2.1 Defining Variables

• You define a variable when your app needs to remember something that is not being stored within a component property. – For example, a game app might need to

remember what level the user has reached. • If the level number is not something the user will

see, you’d define a variable to store it.

靜宜大學資管系 楊子青 8

Defining Variables

1. 拖曳出 initialize global name to

靜宜大學資管系 楊子青 9

Defining Variables

2. 設定變數名稱

3. 設定初值

靜宜大學資管系 楊子青 10

2.2 Setting and getting a Variable

• 設定 ( 變更 ) 變數值

選擇變數名稱

靜宜大學資管系 楊子青 11

Setting and getting a Variable

• 取得變數值

選擇變數名稱

靜宜大學資管系 楊子青 12

2.3 Setting a Variable to an Expression

• Incrementing a Variable

• Building Complex Expressions

靜宜大學資管系 楊子青 13

Math drawer

• In the Math drawer, App Inventor provides a wide range of mathematical functions.

靜宜大學資管系 楊子青 14

2.4 Displaying Variables

• Changing a variable has no direct effect on the app’s appearance.– When you modify a component property, the user

interface is directly affected. This is not true for variables.

– This is one of the advantages of storing data in a variable as opposed to a component property

• it allows you to show just the data you want when you want to show it.

• It also allows you to separate the computational part of your app from the user interface, making it easier to change that user interface later.

靜宜大學資管系 楊子青 15

HelloPurr_Extend

靜宜大學資管系 楊子青 16

1. 複製專案進行修改• 開啟 HelloPurr 專案, Save as 為 HelloPurr_Extend

靜宜大學資管系 楊子青 17Media 部分,以 Upload File 加入獅子圖片 (lion.jpg) 與獅吼聲音 (roar.m

p3)

靜宜大學資管系 楊子青 18

回顧: LabelName 的 Text 屬性,決定顯示文字內容

靜宜大學資管系 楊子青 19

回顧: Button1 的 Image 屬性,決定該按鈕的長相 ( 顯示哪張圖片 )

靜宜大學資管系 楊子青 20

回顧: Sound1 的 Source 屬性,決定播放哪個聲音檔

靜宜大學資管系 楊子青 21

如何動態調整顯示文字?圖片?聲音?

靜宜大學資管系 楊子青 22

執行結果:初次播放 roar.mp3 發生 error

靜宜大學資管系 楊子青 23

Google 找解決方法

靜宜大學資管系 楊子青 24

Screen1.Initialize

靜宜大學資管系 楊子青 25

鱷魚拔牙整人玩具http://www.i-gamer.net/play/2978.html

靜宜大學資管系 楊子青 26

2. 按圖片,第 6 次出現獅子

靜宜大學資管系 楊子青 27

3. 隨機第 2-6 次出現獅子

top related