如何在 PyGame 中使用鼠标缩放和旋转图像？

原文:https://www . geeksforgeeks . org/如何使用鼠标来缩放和旋转 pygame 中的图像/

在本文中，我们将讨论如何在 Pygame 中使用鼠标变换图像(即缩放和旋转图像)。

方法

第一步:首先导入库 Pygame 和数学。

import pygame
import math
from pygame.locals import *

第二步:现在，把我们想在游戏中使用的颜色作为输入。

color_1 = #RGB value of color 1
color_2 = #RGB value of color 2
color_n = #RGB value of color n

步骤 3: 然后，初始化构造函数

pygame.init()

第四步:设置你的 GUI 游戏的尺寸。

w, h = #Width dimension, #Height dimension
screen = pygame.display.set_mode((w, h))

第五步:设置运行游戏的运行值，即可以移动的角度。

running = True
angle = 0
scale = 1

第六步:接下来，把我们想用鼠标移动的图像作为输入

img_logo = pygame.image.load('#Enter the image url')
img_logo.convert()

第七步:在图像周围画一个边框。

rect_logo = img_logo.get_rect()
pygame.draw.rect(img_logo, color_1, rect_logo, 1)

第八步:定位 GUI 游戏的中心，得到鼠标的位置。

center = w//2, h//2
mouse = pygame.mouse.get_pos()

步骤 9: 将图像存储在一个新的变量中，并在图像周围构建一个矩形。

img = img_logo
rect = img.get_rect()
rect.center = center

第十步:设置你希望你的应用在运行状态下要做的事情。

while running:
    for event in pygame.event.get():
  • 步骤 10.1: 一旦 app 处于运行状态，如果用户想退出，就让其退出。
        if event.type == QUIT:
            running = False
  • 步骤 10.2: 在用户不想退出的情况下，设置图像应该旋转到什么角度。
        if event.type == KEYDOWN:
            if event.key == K_ra:
                if event.mod & KMOD_SHIFT:

                    # angle at which it should move left
                    angle -= 
                else:

                    # angle at which it should move right
                    angle +=
  • 步骤 10.3: 此外，设置图像大小应该以什么比例减小或增大。
            elif event.key == K_sa:
                if event.mod & KMOD_SHIFT:
                    scale /= #scale at which the image size should decrease
                else:
                    scale *= #scale at which the image size should increase
  • 步骤 10.4: 设置图像将旋转或调整大小的坐标、角度和比例。
        elif event.type == MOUSEMOTION:
  • 步骤 10.4.1: 将事件的当前位置存储在新变量中。
            mouse = event.pos
  • 步骤 10.4.2: 借助鼠标变量和图像中心定位笛卡尔坐标，旋转图像..
            x = mouse[0] - center[0]
            y = mouse[1] - center[1]
  • 第 10.4.3 步:进一步借助公式√x 2 +y 2 计算两点(0，0)和(x，y)之间的距离
            d = math.sqrt(x ** 2 + y ** 2)
  • 步骤 10.4.4: 现在，使用 Python 方法 math.atan2() 计算图像应该旋转的角度(以度为单位)，该方法以弧度为单位返回 y/x 的反正切。
            angle = math.degrees(-math.atan2(y, x))
  • 步骤 10.4.5: 使用函数 abs 计算图像大小应该减小或增大哪个比例，该函数返回数字的大小。
            scale = abs(5 * d / w)
  • 步骤 10.4.6: 使用旋转缩放功能计算运行状态下图像的更新位置，旋转缩放功能是一种组合的缩放和旋转变换。
            img = pygame.transform.rotozoom(img_logo, angle, scale)
  • 步骤 10.4.7: 围绕更新后的图像构建矩形
            rect = img.get_rect()
            rect.center = center

步骤 11: 接下来需要设置屏幕颜色和屏幕上的图像。

    screen.fill(color_3)
    screen.blit(img, rect)

第 12 步:稍后，画出 长方形线条和 圆圈 ，这将有助于移动图像。

 pygame.draw.rect(screen, color_2, rect, #thickness of rectangle)
    pygame.draw.line(screen, color_3, center, mouse, #Thickness of line)
    pygame.draw.circle(screen, color_1, center, #radius of circle, #thickness of circumference)
    pygame.draw.circle(screen, color_2, mouse, #radius of circle, #thickness of circumference)

*步骤 13:* 此外，更新在 GUI 游戏中所做的更改。

 pygame.display.update()

*第 14 步:*最后退出 GUI 游戏。

pygame.quit()

下面是实现。

计算机编程语言

# Python program to transform the 
# image with the mouse

#Import the libraries pygame and math
import pygame
import math
from pygame.locals import *

# Take colors input
RED = (255, 0, 0)
BLACK = (0, 0, 0)
YELLOW = (255, 255, 0)

#Construct the GUI game
pygame.init()

#Set dimensions of game GUI
w, h = 600, 440
screen = pygame.display.set_mode((w, h))

# Set running, angle and scale values
running = True
angle = 0
scale = 1

# Take image as input
img_logo = pygame.image.load('gfg_image.jpg')
img_logo.convert()

# Draw a rectangle around the image
rect_logo = img_logo.get_rect()
pygame.draw.rect(img_logo, RED, rect_logo, 1)

# Set the center and mouse position
center = w//2, h//2
mouse = pygame.mouse.get_pos()

#Store the image in a new variable
#Construct the rectangle around image
img = img_logo
rect = img.get_rect()
rect.center = center

# Setting what happens when game is
# in running state
while running:
    for event in pygame.event.get():

        # Close if the user quits the game
        if event.type == QUIT:
            running = False

        # Set at which angle the image will
        # move left or right
        if event.type == KEYDOWN:
            if event.key == K_ra:
                if event.mod & KMOD_SHIFT:
                    angle -= 5
                else:
                    angle += 5

            # Set at what ratio the image will
            # decrease or increase
            elif event.key == K_sa:
                if event.mod & KMOD_SHIFT:
                    scale /= 1.5
                else:
                    scale *= 1.5

        # Move the image with the specified coordinates,
        # angle and scale        
        elif event.type == MOUSEMOTION:
            mouse = event.pos
            x = mouse[0] - center[0]
            y = mouse[1] - center[1]
            d = math.sqrt(x ** 2 + y ** 2)
            angle = math.degrees(-math.atan2(y, x))
            scale = abs(5 * d / w)
            img = pygame.transform.rotozoom(img_logo, angle, scale)
            rect = img.get_rect()
            rect.center = center

    # Set screen color and image on screen
    screen.fill(YELLOW)
    screen.blit(img, rect)

    # Draw the rectangle, line and circle through
    # which image can be transformed 
    pygame.draw.rect(screen, BLACK, rect, 3)
    pygame.draw.line(screen, RED, center, mouse, 2)
    pygame.draw.circle(screen, RED, center, 6, 1)
    pygame.draw.circle(screen, BLACK, mouse, 6, 2)

    # Update the GUI game
    pygame.display.update()

# Quit the GUI game
pygame.quit()

*输出:*

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